I Already Filed Taxes But Forgot a W-2. What Should I Do?

If you filed your tax return but forgot to include a W-2 form, you should correct the mistake proactively. This is a common issue, and the Internal Revenue Service (IRS) has a clear process for correction. The IRS matches income reported by employers on W-2s with individual tax returns, and a discrepancy will likely be flagged, leading to notices and potential penalties. Correcting the error yourself allows you to manage the process and mitigate negative consequences.

Required Information and Forms to Amend Your Return

Before you can correct your return, you must gather the necessary documents. The first is the W-2, Wage and Tax Statement, that was originally omitted. This form contains the details about your additional income and the corresponding taxes that were withheld. If you do not have the W-2, you should contact the employer who issued it to request a copy.

Next, you will need a copy of the original tax return you filed, Form 1040. This document contains all the figures you initially reported. You will need to reference specific lines from this return, such as your original adjusted gross income (AGI), deductions, and total tax liability, to show the IRS what is being changed.

The final document is Form 1040-X, Amended U.S. Individual Income Tax Return. This is the specific form used to correct a previously filed Form 1040. This form is not a replacement for your original return; it is a supplementary filing that details the specific changes from the original submission.

Completing and Filing Form 1040-X

Once you have your documents, you can complete Form 1040-X. The form is structured with three main columns. Column A, “Original amount,” is where you will enter the figures exactly as they appeared on your initial tax return, transferring the numbers directly from your original Form 1040.

Column C, “Correct amount,” is where you will report the new, updated figures after including the information from your forgotten W-2. This means you will need to recalculate your total income, AGI, and tax liability with the additional wages and withholdings. The difference between the figures in Column A and Column C is then entered into Column B, “Net change.” This column shows the IRS the specific adjustments you are making to your income and credits.

Form 1040-X requires a written explanation of the changes in Part III. You must clearly state why you are amending your return; for example, “I am amending my return to include a W-2 from [Employer’s Name] that was omitted from my original filing.” You must also attach a copy of the newly included W-2 form to the amended return.

After completing the form, you can file it electronically or by mail. Many tax software programs support e-filing Form 1040-X. If filing by mail, the IRS website provides a list of mailing addresses based on the state where you live.

Managing Financial Consequences

Filing an amended return means you will either owe additional tax or be due a larger refund. If the forgotten W-2 increases your total tax liability, you will owe more tax. It is best to pay this amount when you file Form 1040-X to minimize interest and penalties. The IRS offers several payment options, including Direct Pay or payment by debit or credit card.

The IRS will calculate any applicable interest and penalties and send you a separate notice. The penalty for failure to pay is a percentage of the unpaid taxes for each month they are late, up to a 25% cap. Filing the amendment and paying promptly can reduce these additional charges.

If the withholdings on your forgotten W-2 are greater than the additional tax you owe, you will be due a larger refund. It can take up to 16 weeks for the IRS to process an amended return. You can check the status of your amended return using the “Where’s My Amended Return?” tool on the IRS website starting about three weeks after you file.

Amending Your State Tax Return

Changes to your federal tax return almost always require an amendment to your state tax return. Most state income tax calculations begin with the federal AGI. Since forgetting a W-2 changes your federal AGI, your state taxable income will also change, requiring you to file a separate amended return with your state’s tax agency.

The process for amending a state return varies, as each state has its own forms and procedures. You will need to visit the website for your state’s department of revenue to find the correct amended tax form and instructions. You should complete your federal Form 1040-X first, as you will need the corrected federal information for the state return.

Failing to amend your state return after correcting your federal return can lead to notices and penalties from your state tax authority. It is best to handle both amendments around the same time to ensure all your tax obligations are met.