To attach a W-2 to your tax return on paper, staple Copy B of each W-2 to the front of your Form 1040 before mailing. If you e-file, there is no physical attachment: you type the numbers from each W-2 box into your tax software, or let the software import them, and the return travels electronically to the IRS.
Pick the Right Copy Before You Attach Anything
Your employer sends several copies of Form W-2, and only one goes to the IRS with a federal return. Copy B is the federal copy. Copy 2 is for your state, city, or local tax department if you owe income tax at those levels. Copy C stays with you as your personal record.
Before you file, compare the W-2 against your final pay stub for the year, especially Box 1 (wages) and Box 2 (federal income tax withheld). If a figure looks wrong, ask your employer’s payroll or HR contact for a corrected Form W-2c. Fixing it before you file is far easier than amending later.
Attaching Copy B to a Paper Return
If you mail Form 1040 or 1040-SR, attach Copy B of every W-2 you received to the front of the return.1Internal Revenue Service. Topic No. 301, When, How and Where to File The IRS instructions say to “attach” the forms without prescribing an exact spot, and a staple along the left margin of page one is standard practice. Keep the staple clear of any printed dollar amounts, your name, and your Social Security number so IRS staff can read everything without pulling it off.
If you received a Form W-2c correcting an earlier W-2, attach copies of both the original W-2 and the W-2c to the front of the return.1Internal Revenue Service. Topic No. 301, When, How and Where to File Other schedules and forms go behind the return, ordered by the attachment sequence number printed in each form’s upper-right corner.2Internal Revenue Service. 2025 Instructions for Form 1040
One exception if you owe a balance and are mailing payment with Form 1040-V: do not staple the voucher or your check to the return or to each other. They go loose in the envelope.3Internal Revenue Service. 2025 Form 1040-V Payment Voucher The W-2 still gets stapled to the 1040 itself.
Entering W-2 Data When You E-File
Electronic filing replaces the physical attachment. Instead of mailing Copy B, you enter the information from each W-2 box into your tax software. Most programs start by asking for the nine-digit Employer Identification Number in Box b of the W-2, which links your reported wages to what your employer already filed with the Social Security Administration.
Many tax software products offer a W-2 import feature. After you enter the EIN, the program checks whether your employer’s payroll provider participates in electronic data sharing. If it does, the software can pull your W-2 data automatically and pre-fill the boxes for you to review. If import is not available, you enter the figures manually: typically Boxes 1 through 20, plus any entries in the lettered boxes at the top and any Box 12 codes with their amounts.
You do not need to buy software to e-file. IRS Free File offers free access to tax preparation software if your adjusted gross income is $89,000 or less, and IRS Free File Fillable Forms are available regardless of income for people comfortable preparing their own returns.4Internal Revenue Service. 2026 Tax Filing Season Opens With Several Free Filing Options Available Active-duty military members and their families can use MilTax at no cost through the Department of Defense.
If a Corrected W-2 Arrives After You File
If you receive a Form W-2c or an additional W-2 after filing, you may need to amend your return using Form 1040-X. Attach a copy of the corrected or additional W-2 to the front of the 1040-X.5Internal Revenue Service. Instructions for Form 1040-X The form uses three columns: Column A for the original amounts, Column B for the increase or decrease, and Column C for the corrected amounts. Part II asks for an explanation, and a short note such as “received a corrected W-2 after filing” is enough.
To claim a refund through an amendment, you generally must file Form 1040-X within three years of the date you filed the original return, or within two years of the date you paid the tax, whichever is later.6Internal Revenue Service. Amended Returns and Form 1040-X Processing typically takes 8 to 12 weeks and can stretch to 16.
If Your W-2 Never Arrives
Employers must send W-2s by the end of January. If yours has not arrived, contact your employer first. If you still do not have it by the end of February, call the IRS at 800-829-1040 with your name, address, Social Security number, dates of employment, and your employer’s contact information. The IRS will reach out to the employer and send you Form 4852, which serves as a substitute for the missing W-2.7Internal Revenue Service. If You Don’t Get a W-2 or Your W-2 Is Wrong
If the filing deadline arrives with no W-2 in hand, use your pay stubs to estimate wages and withholdings, complete Form 4852, and attach it to your return in place of the W-2.8Internal Revenue Service. About Form 4852, Substitute for Form W-2 The form asks how you calculated the numbers (for example, “used final pay stub”) and what you did to try to obtain the actual W-2.9Internal Revenue Service. Form 4852, Substitute for Form W-2 Filing with a reasonable estimate beats missing the deadline; you can amend later if the real W-2 shows different figures. The deadline for 2025 returns is April 15, 2026.