# Envelopes, Cards & Forms

Three products share this shelf, and each is shaped by whoever handles it next. Envelopes are sized to the insert and to USPS sorting machines, so square and clasp envelopes cost more to mail. Cards are sold under the envelope name they fit. Tax kits are bought by form number and year, with red scannable Copy A for paper filing.

## How it works

Nothing here does work on its own. Each item is a carrier whose size, surface and ink are set by the machine or office that handles it next. USPS sorting machines take letters from 3.5 to 6 1/8 inches high and 5 to 11 1/2 inches long, with length between 1.3 and 2.5 times the height; anything square, rigid, clasped or tied pays a nonmachinable surcharge, and anything bigger mails as a large envelope (a flat). Inside that box, an envelope is sized to its insert: a #10 takes a letter folded in three, an A7 takes a 5 x 7 card. IRS scanners read Copy A of most 1099s only in a specific red ink, so a home-printed 1099-NEC or 1099-MISC Copy A is refused. Carbonless forms copy through microcapsules that burst under pen pressure, so they need a pen or an impact printer. [1] [3] [10] [4] [8] [9]

| Family | What it is | Suits |
|---|---|---|
| Envelopes | Paper envelopes from small remittance sizes to 10 x 13 catalog envelopes, plain, window or security-tinted. Padded, bubble and poly mailers belong to Shipping Boxes & Mailers (shipping-boxes). | Business letters, invoices, statements, cards and invitations, flat documents. |
| Cards | Blank index cards, folded greeting and note cards (blank or printed for an occasion), and postcards meant to mail without an envelope. Blank or ruled index cards stay here even when titled flash cards; printed study sets go to Flash Cards & Reading Toys (flash-cards). Letter-size sheets that tear into postcards, and cardstock sold by the sheet, go to Paper & Cardstock (paper). | Study and filing, personal notes and invitations, short mailed messages. |
| Forms | Pre-printed paper you fill in: IRS information returns such as 1099 and W-2 kits, checks, and carbonless receipt, invoice and order books. Thermal receipt rolls go to Paper & Cardstock (paper) and check registers to Notebooks, Notepads & Sticky Notes (notebooks). | Small businesses, payroll, landlords, trades that write receipts on site. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · Envelopes, cards or forms
    envelopes : ask Envelope size, Window, Closure : skip Card type, Form type, Form number, Tax year, Scannable red Copy A, Copies per set, Check position
    cards : ask Card type : skip Form type, Form number, Tax year, Scannable red Copy A, Copies per set, Check position
    forms : ask Form type : skip Card type, Occasion
  section 2 · Envelope size
    #10 / #9 : ask Window, Security tint
    9 x 12 / 10 x 13 / C4 : ask Booklet or catalog opening, Postage class
    square : ask Postage class
  section 3 · Card type
    index cards : ask Card size, Ruling : skip Envelopes included, Occasion
    greeting or note cards : ask Occasion, Card size, Envelopes included : skip Ruling
    postcards : ask Card size, Postage class : skip Ruling
  section 4 · Form type
    tax information returns : ask Form number, Tax year, Scannable red Copy A, Copies per set, How it is filled in, Envelopes included : skip Check position
    carbonless business forms : ask Copies per set, How it is filled in : skip Form number, Tax year, Scannable red Copy A, Check position
    checks : ask Check position, How it is filled in : skip Form number, Tax year, Scannable red Copy A
```

1. **Envelopes, cards or forms.** Envelopes, cards, or forms like 1099s and receipt books?
   The three families share almost no facets: envelope size and closure mean nothing for a 1099 kit, and tax year means nothing for an envelope. One answer removes two of the three families and decides every later question.
   If envelopes: ask Envelope size, Window, Closure; skip Card type, Form type, Form number, Tax year, Scannable red Copy A, Copies per set, Check position.
   If cards: ask Card type; skip Form type, Form number, Tax year, Scannable red Copy A, Copies per set, Check position.
   If forms: ask Form type; skip Card type, Occasion.
   Skip if already known: a query that names envelopes, a card type, a form number or a receipt book.

2. **Envelope size.** A folded letter, a flat page, or a card?
   Envelopes are bought by size name, and the insert decides the name. The answer picks one of three size ladders (business, catalog, A-series) and with it the postage class: catalog sizes mail as flats, square envelopes pay a surcharge.
   If #10 or #9: ask Window, Security tint.
   If 9 x 12 or 10 x 13 or C4: ask Booklet or catalog opening, Postage class.
   If square: ask Postage class.
   Skip if already known: a size name in the query, such as #10, A7 or 9 x 12, the card size, when the buyer is matching envelopes to cards.

3. **Card type.** Index cards, greeting or note cards, or postcards?
   Index cards are bought by size and ruling, greeting cards by occasion, size and envelopes, and postcards by whether they mail at the card price. Each answer leaves a set with its own two or three facets.
   If index cards: ask Card size, Ruling; skip Envelopes included, Occasion.
   If greeting or note cards: ask Occasion, Card size, Envelopes included; skip Ruling.
   If postcards: ask Card size, Postage class; skip Ruling.
   Skip if already known: a query that says index, greeting, thank-you, birthday, note card or postcard.

4. **Form type.** Tax forms, checks, or receipt and invoice books?
   Tax kits turn on form number, year and Copy A; receipt books on copies per set and how they are filled in; checks on where the check sits on the sheet. Each answer leaves a different set of deciding facts.
   If tax information returns: ask Form number, Tax year, Scannable red Copy A, Copies per set, How it is filled in, Envelopes included; skip Check position.
   If carbonless business forms: ask Copies per set, How it is filled in; skip Form number, Tax year, Scannable red Copy A, Check position.
   If checks: ask Check position, How it is filled in; skip Form number, Tax year, Scannable red Copy A.
   Skip if already known: a form number in the query, such as 1099-NEC or W-2, a query that says receipt book, invoice book or checks.

## What to surface

### Envelopes, cards or forms

Which of the three products on this shelf the buyer wants: an envelope, a blank card, or a pre-printed form to fill in. The three families share almost no deciding facts. Envelopes turn on size, window and closure; cards on card type and envelope fit; forms on form type, tax year and copy count. Asking a form question of an envelope buyer reads as not knowing the shelf. [10] [4] [9]

Values: envelopes, cards, forms.
Question to ask: Envelopes, cards, or forms like 1099s and receipt books?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost low. Look for it as: The product noun in the title: envelope, card, postcard, form, 1099, W-2, receipt book, checks.
Classify from the title noun. Kits that bundle forms with envelopes are forms.

### Card type

Which kind of card, within the cards family: blank index cards, folded greeting or note cards, or postcards that mail without an envelope. Each type is bought on different facts. Index cards on size and ruling; greeting and note cards on occasion, size and whether envelopes come with them; postcards on whether they meet the USPS card size so they mail at the cheaper card price. [20] [17] [3]

Values: index cards, greeting or note cards, postcards.
Question to ask: Index cards, greeting or note cards, or postcards?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: The product noun in the title.

### Form type

Which kind of form, within the forms family. Answer rule: tax forms means IRS information returns (1099, W-2, 1096), receipt and invoice books means carbonless business forms. Tax forms are governed by IRS form, ink and year rules; carbonless books by how many copies each set makes and how they are filled in; checks by where the check sits on the sheet and by the bank's magnetic reading line. The answer sets which facets matter next. [4] [8] [22]

Values: tax information returns, checks, carbonless business forms, other forms.
Question to ask: Tax forms, checks, or receipt and invoice books?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: The form number or noun in the title.

### Envelope size

The named size of an envelope, such as #10 or A7, which fixes its dimensions. Answer rule: folded letter means #10 (DL for A4 paper), flat page means 9 x 12 (C4), a card means the A-series size named for it, or square for a square card. The insert decides the size. A #10 (4 1/8 x 9 1/2 in) takes a letter folded in three; 9 x 12 takes it unfolded; A2, A7 and A9 take 4.25 x 5.5, 5 x 7 and 5.5 x 8.5 in cards. Size also sets postage: 9 x 12 and C5 mail as flats, and square envelopes pay a surcharge. [10] [11] [13] [1] [23]

Values: #6 3/4, #9, #10, A2, A6, A7, A9, 6 x 9, 9 x 12, 10 x 13, square, DL, C5, C4.
Question to ask: A folded letter, a flat page, or a card?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: In the title, as the name and inches together, e.g. '#10 Double Window Envelopes (4 1/8 x 9 1/2)' on Envelopes.com.
When only inches are given, map them to the name with the lookup in envelope_height_in.
Chart: USPS letter-size box.

### Tax year

The calendar year whose payments the form reports, which decides which form revision is current. The IRS revises information returns irregularly. A revision is first used for the year in its revision date and has a blank 'For calendar year' line, so it stays in use until a newer one replaces it. For 2026 payments the December 2026 1099-NEC replaces the April 2025 revision, so this season a 2025 NEC kit is the wrong product. [4] [23]

Question to ask: Which year's payments are you reporting?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: A year in nearly every kit title ('2026'); 2025 and 2024 kits stay on sale.
When the title has no year, read the revision line on the form image ('Rev. December 2026'), a page visit per kit, so top N only. Treat a kit with no year as unknown, never as current.

### Window

A clear opening in the envelope front that shows an address printed on the document inside. Windows come on business sizes and save addressing invoices, statements and checks. A single window shows the recipient; a double window shows sender and recipient. There is no universal window position, so the window has to line up with where the address lands on the folded document. Paper windows do not make a letter nonmachinable. [13] [11] [14] [1] [23]

Values: no window, single window, double window.
Question to ask: Is the address printed on the letter inside?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title: 'Single Window', 'Double Window', 'Windowless' (Amazon and Envelopes.com). Window position in inches is on the product page only.
Position matters for software-printed invoices and tax forms; backfill it from the product page for the top N window envelopes.
Chart: outline of the envelope with the window drawn to position.

### Closure

How the envelope flap shuts: moistened gum, a peel-off strip, two adhesive surfaces pressed together, or a metal clasp or string tie. Gummed flaps need moistening; peel and seal and press-seal flaps close dry, which suits a stack of envelopes sealed by hand. Clasps, strings and buttons hold a flap without glue, but on a letter-size envelope they make the piece nonmachinable, so each one costs more to mail. [12] [10] [1] [3] [23]

Values: gummed, peel and seal, press seal, clasp, string and button.
Question to ask: Lick-to-seal, peel-and-seal, or a metal clasp?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title: 'Self-Seal', 'Peel and Seal', 'Gummed', 'Clasp' (Amazon and Envelopes.com). Brand names for press seal vary (Simple Seal, Redi-Seal).
Map brand names for press-together and liner closures to the two values before filtering.

### Occasion

What a greeting or note card is printed for: blank inside, thank you, birthday, or a mixed all-occasion box. For a printed card the occasion decides the pick before size or envelopes: a birthday box is no use for thank-you notes. Blank cards take any message, and assortment boxes mix occasions in one pack. Titles state it. [23]

Values: blank inside, thank you, birthday, all-occasion assortment, other occasion.
Question to ask: Blank inside, thank-you, birthday, or a mixed box?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title: 'Blank Inside', 'Thank You Cards', 'Happy Birthday Cards', 'All-Occasion'.
Title text; a mixed box is all-occasion assortment.

### Card size

The flat size of the card in inches, which for index cards is the product name and for note cards often follows the envelope it fits. Index cards come 3 x 5, 4 x 6 and 5 x 8 in, and a card box or file is sized to one of them. Note cards come 3.5 x 5, 4 x 6 and 5 x 7 in, and flat card stock is sold under its envelope name: an A2 card is 4.25 x 5.5 in, an A7 card 5 x 7 in, each an eighth to a quarter inch smaller than its envelope. [20] [18] [17] [11] [23]

Values: 3 x 5, 3.5 x 5, 4 x 6, 5 x 8, A2 (4.25 x 5.5), A7 (5 x 7), other.
Question to ask: Which size: 3x5, 4x6, 5x7, or another?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title, in inches or as the A-series name; for 'other', keep the listed inches.
Chart: USPS letter-size box.

### Copies per set

How many copies each form set makes, as separate sheets or a carbonless set, from 2-part upward. Each extra part is one more copy for the customer, the payee, the office, the file or a state. Receipt books sell as 2- and 3-part carbonless sets; 1099 kits as 3- and 4-part, W-2 kits as 4- and 6-part. In a carbonless set the top sheet is coated on the back, middle sheets on both sides, the last on the front. Buyers choose by how many people need a copy. [8] [9] [4] [7] [23]

Values: 2-part, 3-part, 4-part, 5-part or more.
Question to ask: How many copies each: two, three, four or more?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title: '2-Part', '3-Part Carbonless', '4 Part Tax Forms Kit', '6 Part'.
Title text first, then the brand or product page; cheap to extract across the catalog.

### Security tint

A printed pattern inside the envelope that stops the contents showing through the paper. Checks, statements, payroll and tax forms carry numbers someone could read by holding the envelope to a light. Tint is sold on #10, #9, #6 3/4, 6 x 9, 9 x 12 and 10 x 13 sizes and on W-2 and 1099 envelopes. A photo of the outside cannot show it. [15] [12] [23]

Question to ask: Mailing checks or account numbers?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title as 'Security Tinted' or 'Security Tint' (Amazon and Envelopes.com).
Title text first, then the brand or product page; cheap to extract across the catalog.

### Envelopes included

Whether a pack of greeting, note or postcards, or a tax-form kit, comes with envelopes that fit it. A pack with envelopes fits by construction. A card pack without needs the matching A-series envelope bought separately, and a card a quarter inch too big will not go in. Tax kits are sold with and without double-window envelopes, and envelopes made for one year's form layout are sold as not fitting the next. Counts can differ, so read envelopes per item. [12] [17] [23]

Question to ask: Need envelopes with them?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title: 'with Envelopes', 'Includes 50 Envelopes', '(Without Envelope)'.
Title text first, then the brand or product page; cheap to extract across the catalog.

### Ruling

Whether an index card is blank, lined or printed with a grid. Ruled cards suit notes and recipes, blank cards suit flash cards and drawing, and grid cards suit diagrams. A photo usually shows it, so it is a card-face annotation rather than a search field. [20] [23]

Values: blank, ruled, grid.
Question to ask: Lined, blank, or grid?

Used as: shown on the card, filter. Data: on the listing, backfill cost low. Look for it as: In the title: 'Ruled', 'Lined', 'Blank'; the main photo shows it too.
Title text first, then the brand or product page; cheap to extract across the catalog.

### Form number

Which IRS form a tax kit holds, such as 1099-NEC (nonemployee compensation), 1099-MISC, W-2 (wage and tax statement), or the 1096 and W-3 transmittals. A tax-form buyer needs one form, not 'tax forms': a 1099-NEC kit cannot report wages, and a W-2 kit cannot report contractor pay. Kit titles lead with the form number, often with the transmittal bundled, and tax envelopes are sold for named forms and layouts. [4] [6] [7] [23]

Values: 1099-NEC, 1099-MISC, 1099-INT, 1099-DIV, 1099-R, 1096, W-2, W-3, other.
Question to ask: Which form: 1099-NEC, 1099-MISC, W-2, or another?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: Leads the kit title: '1099 NEC Forms 2026', 'W2 2026 Tax Forms Kit'.
Title text. Blank multi-use stock ('use for W2 or 1099') is other.

### How it is filled in

Whether a form or check is written by hand, run through an impact (dot-matrix) printer, or printed on a laser or inkjet printer. Carbonless copies form only where pressure bursts the dye capsules, from a ballpoint pen or an impact printer such as a dot-matrix. So continuous carbonless 1099 kits are for pin-fed dot-matrix printers, laser kits and computer checks are for software printing, and manual checks and receipt books are written by hand. A form made for one method is the wrong buy for another. [9] [8] [24] [23]

Values: by hand, impact printer, laser or inkjet.
Question to ask: Writing these by hand, or printing from software?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title or bullets: 'Laser', 'Laser/Inkjet', 'Dot Matrix', 'Continuous', 'Manual Checks'.
Read the title, then the bullets; receipt books with a cover and stub are by hand.

### Scannable red Copy A

Whether the form's Copy A is the red, scannable version the IRS accepts on paper, rather than black recipient copies only. For 1099-NEC, MISC, INT, DIV, R and most other 1099s, paper Copy A must be printed in a specific red dropout ink; a Copy A printed at home from the IRS PDF cannot be scanned and can draw a penalty. A few low-volume forms, such as 1099-Q and 1099-SA, are fillable PDFs printed in black. Filers of 10 or more returns must e-file. W-2 Copy A has a black-ink route. [4] [6] [5] [7] [23]

Question to ask: Filing paper forms by mail, or filing online?

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Some titles say 'Red Scannable Copy A' or 'Red Ink'; recipient-only packs say 'Copy B' or 'Blank'.
Answer rule: mailing paper forms means yes, filing online means no. When the title is silent, confirm red Copy A from the kit contents on the brand page, a page visit per kit, so do the top N first.

### Check position

Where the check sits on a sheet of business checks: on top, in the middle or at the bottom with voucher stubs, or three checks to a page. Accounting software prints payee, amount and date onto pre-printed check sheets, so the buyer picks the layout their software prints: check on top with two stubs below, in the middle, or at the bottom. Three-to-a-page sheets come as computer and manual checks. Every check title states the position. [24] [25] [23]

Values: check on top, check in middle, check on bottom, 3 per page.
Question to ask: Check on top, middle, bottom, or three per page?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title: 'Check on Top', 'Checks in The Middle', 'Check on Bottom', '3 per Page'.
Title text; 'Top Computer Checks' is check on top.
Chart: sheet outline with the check drawn in its position.

### Booklet or catalog opening

Whether a large envelope opens along its long side (booklet) or its short side (catalog, also called open end). Booklet envelopes take brochures and folded material through the wide side; catalog envelopes take flat documents and reports that should not be folded through the narrow end. Both styles are sold at 9 x 12, so the title word (booklet or open side, catalog or open end) decides. [12] [23]

Values: booklet, catalog.

Used as: shown on the card, filter. Data: needs research, backfill cost low. Look for it as: In the title as 'Booklet', 'Open Side', 'Catalog' or 'Open End' (Amazon and Envelopes.com).
Title text first, then the brand or product page; cheap to extract across the catalog.

### Postage class

Which USPS price an empty piece of this size and closure pays: postcard, letter, letter plus the nonmachinable surcharge, or large envelope (flat). A letter must be 3.5 to 6 1/8 in high and 5 to 11 1/2 in long, with length 1.3 to 2.5 times height. Square envelopes, clasps, strings and a short-side address add a surcharge, and so does any piece over 4.25 in high or 6 in long that is thinner than 0.009 in. 9 x 12 and C5 mail as flats. Postcards over 4.25 x 6 in pay the letter price. [1] [2] [3] [11] [21] [17]

Values: postcard, letter, letter plus surcharge, flat.

Used as: shown on the card, filter. Data: derived from listing fields, backfill cost low. Look for it as: Not on listings. Compute from envelope_height_in, envelope_length_in or card_size, the closure, and thickness where listed.
Rules from DMM 101 and 201: letter box, aspect ratio, closure, and the 0.009 in minimum thickness for pieces over 4.25 in high or 6 in long. Thickness is rarely listed, so mark such a card's surcharge as unknown unless the listing states thickness.
Chart: USPS letter-size box.

### Envelope height

The envelope's shorter side in inches, as listed beside the size name. Height and length are what the USPS measures: they give the aspect ratio, the postage class, and which inserts fit. Most titles print them beside the name ('4-1/8 x 9-1/2 Inches'), and a named size fixes them, so the pipeline can fill them for every named size. [10] [11] [26] [23]


Used as: shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title beside the size name, e.g. '#10 ... 4-1/8 x 9-1/2 Inches'.
Lookup by name (height x length, in): #6 3/4 3 5/8 x 6 1/2; #9 3 7/8 x 8 7/8; #10 4 1/8 x 9 1/2; A2 4 3/8 x 5 3/4; A6 4 3/4 x 6 1/2; A7 5 1/4 x 7 1/4; A9 5 3/4 x 8 3/4; 6 x 9, 9 x 12 and 10 x 13 as named; DL 4.33 x 8.66 (110 x 220 mm); C5 6.38 x 9.02 (162 x 229 mm); C4 9.02 x 12.76 (229 x 324 mm). Square has no fixed size, so read the listing.
Chart: USPS letter-size box.

### Envelope length

The envelope's longer side in inches, as listed beside the size name. Length over height is the aspect ratio the sorting machines check, and length past 11 1/2 in makes a piece a flat. It also sets how much room a folded letter or card has along its long side. [10] [11] [26] [1]


Used as: shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title beside the size name.
Same lookup as envelope_height_in.
Chart: USPS letter-size box.

### Paper weight

The paper weight as the listing states it: pounds (lb) for 500 sheets of the grade's basis sheet, or grams per square metre (gsm). Titles give weight as '24 LB' or '120GSM', and index cards sometimes as points (pt), which measure thickness, not weight. Pounds compare only within one grade, because bond, cover and index paper use different basis sheets; for bond (17 x 22 in), 20 lb is about 75 gsm and 24 lb about 90 gsm. gsm compares across grades. [19] [6] [12] [27] [23]


Used as: shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title: '24 LB', '28lb', '120GSM', '180gsm', or '7.5 pt.' on index cards; the grade is usually missing.
Store the figure with its unit. Convert pounds to gsm only when the grade is stated; with no grade, show the pound figure as listed and leave gsm blank. Keep pt as listed.
Chart: gsm on one horizontal scale where known, with the listed figure as the label.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Aspect ratio (ratio) | `envelope_length_in / envelope_height_in` | USPS machines take letters only between 1.3 and 2.5. Square envelopes (1.0) fall below; A2 (1.31) sits on the line; #10 (2.3) is safe. [1] [2] [11] |
| Room around the insert (in) | `min(envelope_height_in - insert short side, envelope_length_in - insert long side), with the insert's inches from card_size, or 3 2/3 x 8 1/2 for a letter folded in three` | The check a stationer makes before matching cards to envelopes. A-series pairs run about a quarter inch; under that the card jams, far over it the card slides. [12] [10] [11] |
| Weight in gsm (g/m2) | `the listed gsm figure; else paper_weight (lb) * 1406 / 374 when the grade is bond; else not computed` | Grams per square metre is the one weight that compares across grades and with imported envelopes. A pound figure converts only on its own basis sheet (bond 17 x 22 in), so a pound figure with no stated grade stays unconverted. [19] [6] |

## What you give up

- Square envelopes sit outside the 1.3 to 2.5 aspect ratio the sorting machines take, so each one pays the nonmachinable surcharge on top of the stamp. [1] [3] [17] Board branch: "See more invitation envelopes that mail at the letter price".
- A clasp or string tie holds a flap shut without glue, but on a letter-size envelope it makes the piece nonmachinable and adds the surcharge. A peel and seal flap mails at the normal price. [1] [3] Board branch: "See more letter envelopes without a surcharge".
- A red-ink paper kit lets a small filer mail Copy A, but past 9 returns paper is not allowed, and the IRS IRIS portal files free. Recipient copies can then be plain black forms. [4] [5] Board branch: "See more recipient-copy packs for e-filers".
- Carbonless sets give every party a copy in one pass, but only under pen or impact pressure, so they suit receipts written on site rather than invoices printed from software. [9] [8]

## How to draw it

**USPS letter-size box** (two axis map, shows Envelope size, Envelope height, Envelope length, Postage class, Card size). Height against length, with the letter box (3.5 to 6 1/8 by 5 to 11 1/2 in), the postcard box inside it, and the 1.3 and 2.5 aspect-ratio lines. Each envelope is a point; a buyer sees at once which sizes mail as letters, which as flats, and which sit on the surcharge line. Used today by The dimensions are the USPS's (DMM 101); the drawing is our proposal.. [1] [2]

## Words you will meet

- **#10 envelope**. The standard US business envelope, 4 1/8 x 9 1/2 inches, sized for a letter folded in three.
- **A-series envelope**. North American announcement envelopes such as A2, A7 and A9, named for the card size they hold and unrelated to ISO A paper sizes.
- **DL, C5, C4**. International envelope sizes for A4 paper folded in three, folded once, and flat.
- **Flat**. The USPS name for a large envelope, anything over 6 1/8 inches high or 11 1/2 inches long, which pays a higher price than a letter.
- **Aspect ratio**. An envelope's length divided by its height.
- **Nonmachinable surcharge**. Extra postage the USPS charges on a letter its sorting machines cannot handle, such as a square, rigid or clasped one.
- **Peel and seal**. A flap with a ready adhesive strip under a paper liner you pull off before pressing it shut.
- **Gummed flap**. A flap with dry glue that seals once it is moistened.
- **Security tint**. A printed pattern inside an envelope that hides the contents from someone holding it to a light.
- **Booklet and catalog envelopes**. Large envelopes that open on the long side (booklet) or the short side (catalog).
- **Basis weight**. The weight in pounds of 500 sheets of a paper grade's standard uncut sheet, such as 17 x 22 inches for bond.
- **gsm**. Grams per square metre, a paper weight that compares across all grades.
- **Information return**. A tax form a business files to report payments it made to someone else, such as a 1099-NEC for a contractor.
- **Copy A**. The copy of an information return that goes to the IRS, as opposed to the copies for the recipient and the payer.
- **Red dropout ink**. A specific red ink the IRS scanner ignores, so it reads only the black figures typed or printed into the boxes.
- **Carbonless paper**. Paper coated with tiny dye capsules and a reactive clay, so writing on the top sheet copies onto the sheets below; also called NCR paper.
- **MICR line**. The row of numbers at the bottom of a check, printed in magnetic ink or toner so bank machines can read the routing and account numbers.
- **Points (pt)**. A card thickness figure that some listings give in place of a paper weight.
- **Transmittal**. The cover sheet that goes to the IRS or SSA with a batch of paper forms: Form 1096 for 1099s, Form W-3 for W-2s.
- **Continuous forms**. Forms joined in a strip with punched edge holes, fed through a dot-matrix printer.
- **Voucher check**. A check sheet with perforated stubs that record what the payment was for.

## Where we made a call

- Square and vertical envelopes, and any with a clasp or string, cost more to mail than a standard letter. (confidence high). The DMM aspect-ratio and closure rules, the USPS consumer page and a retailer agree. [1] [3] [17]
- A home-printed Copy A of 1099-NEC, MISC and most other 1099s is not acceptable on paper; a few low-volume forms are fillable PDFs. (confidence high). The form notice and Pub 1179 2.1.5 agree; Pub 1179 2.1.1 lists the fillable exceptions (1099-Q, 1099-SA, 1099-LTC and others). W-2 Copy A differs: SSA-approved black-and-white versions may be printed. [4] [6] [7]
- Red-ink 1099 kits are a product for small filers, because 10 or more information returns must be e-filed. (confidence high). The IRS e-file page (from tax year 2023) and the form notice agree. Larger filers still need recipient copies, which may be black. [5] [4]
- A tax-form kit stays current until the IRS issues a newer revision; for 2026 payments, 2025 1099-NEC kits are out of date. (confidence medium). One source, the IRS revision notice: a revision is first used in its revision year. Listings agree, selling 2025 NEC envelopes as 'Not for 2026 Nec'. Treat a kit with no year as unknown. [4] [23]
- An envelope should be about a quarter inch larger than its insert; this holds for A-series pairs, while business sizes leave more room. (confidence medium). The rule is one retailer's. The A7 and A9 size pairs from two sources match it; the #10 leaves about an inch along its length. [12] [10] [11]
- A pound weight compares only within one paper grade; across grades, compare gsm. (confidence high). Basis sheets differ by grade (Grammage table); Publication 1179 states the bond basis as 17 x 22 inches. [19] [6]
- Window position has no universal standard, so a window envelope must be matched to the document or form it carries. (confidence medium). Wikipedia notes national standards only in some countries; the retailer tells buyers to check alignment before ordering. [11] [13] [16]
- Carbonless forms can cause irritation under some conditions, and current formulations have no clear evidence of significant harm. (confidence medium). Sources disagree. NIOSH found irritation under some conditions but uncertain risk from current paper. Wikipedia adds a bisphenol A claim. We follow NIOSH, the federal review, though it dates from 2000. [8] [9]

## References

1. [USPS Domestic Mail Manual 101, Physical Standards](https://pe.usps.com/text/dmm300/101.htm) (regulator). Supports: Letter size 3.5 to 6 1/8 in high, 5 to 11 1/2 in long, 1/4 in thick; Aspect ratio under 1.3 or over 2.5, clasps and strings make a letter nonmachinable; Paper windows do not make a letter nonmachinable; Postcards 3.5 to 4.25 by 5 to 6 in, 0.007 to 0.016 in thick; Pieces over 4.25 in high or 6 in long need 0.009 in thickness or pay the surcharge.
2. [USPS Domestic Mail Manual 201, Commercial Letters, Cards, Flats and Parcels](https://pe.usps.com/text/dmm300/201.htm) (regulator). Supports: Machinable letters and cards within aspect ratio 1.3 to 2.5; Card price minimum 3.5 x 5 in and 0.007 in thick; Cards over 4.25 in high or 6 in long under 0.009 in thick are nonmachinable letters.
3. [USPS, Mailing Letters](https://www.usps.com/ship/letters.htm) (regulator). Supports: Square or vertical envelopes, clasps, strings and rigid pieces cost more to mail; Postcards mail without an envelope; Unfolded letter pages go in a large envelope, a flat.
4. [IRS Form 1099-NEC (Rev. December 2026), cover notice](https://www.irs.gov/pub/irs-pdf/f1099nec.pdf) (regulator). Supports: Self-printed Copy A from the PDF is not scannable and may draw a penalty; Black recipient copies may be downloaded and printed; 10 or more information returns may require e-filing; A revision not issued annually is first used for the year of its revision date; The December 2026 1099-NEC is for 2026 payments, filed from January 2027; The form has Copy A, Copy 1 for the state, Copy B and Copy 2.
5. [IRS, E-file information returns](https://www.irs.gov/filing/e-file-information-returns) (regulator). Supports: From tax year 2023, 10 or more information returns must be filed electronically; IRIS Taxpayer Portal files information returns free.
6. [IRS Publication 1179 (Rev. 07-2026), substitute Forms 1096, 1098, 1099, 5498 and W-2G](https://www.irs.gov/pub/irs-pdf/p1179.pdf) (regulator). Supports: Copy A of 1099-NEC, MISC, INT, DIV, R and other listed forms needs Flint J-6983 red ink; Fillable online forms such as 1099-Q, 1099-SA and 1099-LTC print in black ink; Non-conforming Copy A substitutes are not acceptable and risk a penalty; Bond paper basis sheet is 17 x 22 in; Form 1096 is the transmittal for paper information returns.
7. [IRS Publication 1141 (Rev. 08-2026), substitute Forms W-2 and W-3](https://www.irs.gov/pub/irs-pdf/p1141.pdf) (regulator). Supports: SSA-approved black-and-white W-2 Copy A may be printed from a printer; Form W-2 is the Wage and Tax Statement; W-3 is its transmittal; Form W-2 has six copies: A, B, C, D, 1 and 2.
8. [NIOSH Hazard Review: Carbonless Copy Paper, Publication 2001-107 (Internet Archive copy)](https://web.archive.org/web/2020id_/https://www.cdc.gov/niosh/docs/2001-107/pdfs/2001-107.pdf) (regulator). Supports: Three-part set: coated-back, coated front and back, coated-front sheets; Microcapsules on the sheet backs carry the dye; Irritation under some conditions; risk from current formulations uncertain.
9. [Wikipedia, Carbonless copy paper](https://en.wikipedia.org/wiki/Carbonless_copy_paper) (primer). Supports: Copies form under ballpoint pressure or impact printing; CB, CFB and CF sheet coatings; Claims a high bisphenol A content in carbonless paper.
10. [Envelopes.com, Envelope Size Guide](https://www.envelopes.com/pages/envelope-size-guide) (spec sheet). Supports: #10 is 4 1/8 x 9 1/2 in and comes plain or with windows; #9 is the reply envelope that fits inside a #10; A2, A6, A7 and A9 dimensions; A7 fits standard greeting cards; Gummed and peel and seal closure definitions.
11. [Wikipedia, Envelope](https://en.wikipedia.org/wiki/Envelope) (primer). Supports: North American and ISO envelope dimensions and aspect ratios; A2 aspect ratio 1.31; #10 holds letter paper folded in thirds; No international standard for window envelopes.
12. [Envelopes.com, FAQs](https://www.envelopes.com/pages/faq) (spec sheet). Supports: An envelope should be about 0.25 in larger than its insert; Booklet opens on the long side, catalog on the short side; Press-together, peel and seal and gummed closures; Same listed weight can feel different.
13. [Envelopes.com, Clear Window Envelopes](https://www.envelopes.com/pages/clear-window-envelopes) (spec sheet). Supports: Single window shows the recipient; double window shows sender and recipient; Match window placement to the address on the folded document.
14. [Envelopes.com, #10 Double Window Envelopes, White with Security Tint 24lb](https://www.envelopes.com/products/envelopes-white-booklet-10-window-double-4-1-8x9-1-2-white-security-item-ws-3342) (retail listing). Supports: Title carries size, window, tint and pound weight; Window positions in inches appear only on the product page.
15. [Envelopes.com, Security Envelopes](https://www.envelopes.com/pages/security-envelopes) (spec sheet). Supports: Security tint is a printed interior pattern hiding text and numbers; Tint sold on #10, #9, #6 3/4, 6 x 9, 9 x 12, 10 x 13 and W-2/1099 sizes.
16. [Envelopes.com, W-2 and 1099 Envelopes](https://www.envelopes.com/pages/tax-shop) (spec sheet). Supports: Tax envelopes must be checked against the form layout and window placement.
17. [Envelopes.com, Types of Envelopes: A Complete Guide](https://www.envelopes.com/blogs/blogs/different-types-of-envelopes) (primer). Supports: Square envelopes may require extra postage; A7 envelopes carry 5 x 7 cards; A2 suits RSVP and thank-you cards.
18. [Cards & Pockets, card stock size menu](https://www.cardsandpockets.com/envelope-size-chart) (retail listing). Supports: Flat cards sold as (A7) 5 x 7 and (A2) 4.25 x 5.5; Flat cards also sold as 3.5 x 5 (RSVP).
19. [Wikipedia, Grammage](https://en.wikipedia.org/wiki/Grammage) (primer). Supports: Basis sheets differ by grade: bond 17 x 22, cover 20 x 26, index 25.5 x 30.5 in; Pound weights compare within one grade.
20. [Wikipedia, Index card](https://en.wikipedia.org/wiki/Index_card) (primer). Supports: Index cards come 3 x 5, 4 x 6 and 5 x 8 in; Sold blank, ruled and grid.
21. [Wikipedia, Postcard](https://en.wikipedia.org/wiki/Postcard) (primer). Supports: USPS postcard limits 3.5 to 4.25 by 5 to 6 in, 0.007 to 0.016 in thick.
22. [Wikipedia, Magnetic ink character recognition](https://en.wikipedia.org/wiki/Magnetic_ink_character_recognition) (primer). Supports: MICR characters are printed in magnetic ink or toner; E-13B is the US font.
23. [Amazon.com search-result titles, 12 queries (tax kits, W-2, checks, envelopes, cards, receipt books)](https://www.amazon.com/s?k=1099+tax+forms+kit+envelopes) (retail listing). Supports: 1099 and W-2 kits sold with and without envelopes, as 3-, 4- and 6-part sets; Continuous 4-part carbonless 1099 kits for dot-matrix printers sold beside laser kits; Kit titles lead with form number and tax year; 2025 and 2024 kits still listed; 2025 1099-NEC envelopes sold as not fitting 2026 forms; Check titles state position: on top, in the middle, on bottom, or 3 per page; Envelope titles state window, closure, security tint, and weight in lb or gsm; Note cards sold 3.5 x 5, 4 x 6 and 5 x 7 in; titles state the occasion; Receipt books titled 2-Part or 3-Part; index cards titled ruled, lined or blank; 9 x 12 envelopes sold in both booklet (open side) and catalog styles.
24. [Checkomatic, Computer Checks](https://www.checkomatic.com/business-checks/computer-checks/) (retail listing). Supports: Computer checks sold with the check on top, in the middle, on the bottom, or 3 on a page; Accounting software prints payee, amount and date onto pre-printed check sheets.
25. [Compuchecks, home page](https://www.compuchecks.com/) (retail listing). Supports: Check stock sold as check on top, check on bottom and 3 on a page.
26. [Wikipedia, Paper size](https://en.wikipedia.org/wiki/Paper_size) (primer). Supports: C4 is 229 x 324 mm, C5 162 x 229 mm, DL 110 x 220 mm.
27. [Wikipedia, Card stock](https://en.wikipedia.org/wiki/Card_stock) (primer). Supports: US card thickness is stated in points (pt), a thickness rather than a weight.