You’re staring at a pile of W-2s and 1099s, ready to mail your 2025 federal tax return. Should you staple, paperclip, or just toss everything in the envelope? The IRS processes millions of returns daily, and a poorly assembled package can cause delays—or worse, trigger an extra letter. Here’s exactly what the agency expects.
Quick Fix Summary
Staple only the income documents that show withholding—W-2s, W-2Gs, and 1099-Rs with federal tax withheld—to the front of Form 1040 at the left edge. Leave everything else loose. Fold the package (don’t roll it), slap on some tracking, and drop it in the mail.
What’s the deal with staples and paperclips anyway?
The IRS scans over 260 million federal returns every year using high-speed machines. Staples or paperclips in the wrong spots can jam the scanners or cover up barcodes, forcing an employee to pull the stack apart by hand. The 2025 Form 1040 Instructions are crystal clear: only staple the withholding documents to the return.
How do I actually do this correctly?
- Round up your paperwork
- Form 1040 (or 1040-SR) – your main document
- Every W-2 that shows federal withholding
- Any 1099-R with Box 4 (federal tax withheld) filled out
- W-2G if you had gambling winnings with tax withheld
- All supporting schedules behind the 1040, ordered by “Attachment Sequence No.”
- Attach the documents that prove withholding
- Lay the 1040 flat on your desk.
- Put the W-2s on the right side of page 1, sorted by the sequence number in the upper-right corner (lowest to highest).
- Drive one staple through all the W-2s and the 1040 at the left edge, about ½ inch from the top. No paperclips allowed.
- Got a 1099-R or W-2G with federal withholding? Stack it with the W-2s and add it to the same staple.
- Organize the rest of your schedules
- Behind the 1040, place Schedule A, Schedule C, etc., in ascending order of their “Attachment Sequence No.”
- Don’t even think about stapling these pages together or to the 1040.
- Fold, weigh, and ship
- Fold the whole package lengthwise so the address shows through the envelope window.
- Check the weight; starting in 2026, first-class postage is $0.68 for the first ounce and $0.24 for each extra ounce.
- Send it via USPS Certified Mail with Return Receipt or a commercial carrier that offers tracking.
What if I messed up?
- Accidentally stapled everything? Pull out the staples before you refold. The IRS can still process the return, but manual handling adds 4-6 weeks to the timeline.
- Forgot to staple a W-2? A paperclip on the W-2 to the front of the 1040 works in a pinch. The IRS prefers staples, but a paperclip won’t jam the scanners.
- State rules don’t match the IRS? California, Massachusetts, and a few others say “do not staple.” Check your state’s 2025 instruction booklet for the exact wording.
How can I avoid future headaches?
- Photocopy everything before mailing; you’ll have the sequence numbers if you need to reference them later.
- Use a ruler to confirm the “Attachment Sequence No.” in the upper-right corner of every schedule—sorting errors delay processing.
- Keep a simple checklist: 1040 + W-2s stapled → schedules in order → sign at the bottom → copy → mail.
- If you e-file, relax—the IRS gets the W-2 data electronically. Only paper filers need to worry about attachment rules.
