What Happens If You Have to Amend Your Taxes?

Discovering an error on a filed tax return is common, and correcting it involves filing an amended return. This process uses a specific form to report changes to your income, deductions, credits, or filing status. Filing an amendment ensures your tax information is accurate and resolves inaccuracies from a previous submission.

Determining if an Amendment is Necessary

An amended return is required for substantive changes to your tax filing. Common reasons include reporting forgotten income, correcting the number of dependents claimed, or using the wrong filing status. You must also amend your return if you failed to claim deductions or credits for which you were eligible, as these errors directly impact your tax liability.

The decision to amend hinges on whether the mistake affects your overall tax calculation. For example, if you discover you could have claimed a significant tax credit for education expenses or realize you omitted income from a side job, an amendment is necessary. The general deadline for filing an amendment to claim a refund is within three years of the date you filed your original return or within two years of the date you paid the tax, whichever is later.

When an Amendment is Not Required

Not every mistake requires an amended return. The IRS often corrects minor mathematical or clerical errors and will notify you by mail of any changes. If you forgot to attach a Form W-2 or another schedule, the IRS will usually send a notice requesting the missing documents rather than requiring a full amendment.

You should not file an amended return to dispute an assessment of additional tax from the IRS. The amendment process is for correcting your own filing errors, not for disagreeing with an IRS determination. To dispute an assessment, follow the specific instructions included in the notice you receive.

Information and Forms for Amending

To begin, gather a copy of your original tax return and any new or corrected documents that prompted the change. These supporting documents could be a corrected Form W-2c, a Form 1099 that was not included in the original filing, or records substantiating a deduction or credit you initially missed.

The specific form used to amend a U.S. individual income tax return is Form 1040-X, Amended U.S. Individual Income Tax Return. This form is available on the IRS website and is designed to clearly show the adjustments being made. A standard Form 1040 cannot be used to amend a previously filed return.

Form 1040-X uses a three-column format. Column A is for the figures as they appeared on your original return. Column C is where you enter the corrected figures. Column B shows the difference between Column A and Column C, representing the net change for each line item.

A part of the form is Part III, Explanation of Changes. In this section, you must provide a clear and concise explanation for each change you are making. For example, if you are adding a dependent, you would state that you are amending the return to add a qualifying child and include their name and Social Security number. Vague or incomplete explanations can lead to processing delays or further inquiries from the IRS.

The Submission Process for an Amended Return

For recent tax years, the IRS allows for electronic filing of amended returns. Most major tax preparation software supports the e-filing of Form 1040-X, which can be a convenient and efficient option.

If you are amending a return for a tax year that is not eligible for e-filing or if you prefer to file by mail, you must send a paper copy of your Form 1040-X. The correct mailing address depends on the state where you live and is listed in the official instructions for Form 1040-X.

When mailing your amended return, you must attach copies of any new or corrected forms that substantiate the changes made. Each amended return must be mailed in its own separate envelope to ensure it is processed correctly.

Post-Filing Outcomes and Procedures

Amended returns are processed manually, and official guidance suggests a processing time of up to 16 weeks. It can often take longer, and in some cases, processing could take more than 20 weeks.

You can begin checking the status of your submission using the “Where’s My Amended Return?” tool on the IRS website starting about three weeks after you file. This online portal allows you to track your Form 1040-X for the current tax year and up to three prior years. You will need to provide your Social Security number, date of birth, and zip code to see if your return has been received, adjusted, or completed.

The outcome of your amendment will result in either an additional refund or a tax liability. If the changes on your Form 1040-X result in a larger refund, the IRS will issue the additional amount. If the amendment results in additional tax owed, you should pay the amount due as soon as possible to minimize interest and penalties. Interest is charged on the unpaid tax from the original due date of the return until the date the tax is paid in full.

Corresponding State Tax Amendments

Changes made on your federal tax return often have a direct impact on your state tax liability. If the adjustments on your Form 1040-X alter your federal adjusted gross income, you will likely need to file a separate amended return with your state’s tax agency.

It is advisable to wait until the IRS has accepted and processed your federal amended return before filing your state amendment. This ensures that the figures on your state return will align with the final, federally approved numbers, which prevents discrepancies and further corrections.

Each state has its own specific forms and instructions for filing an amended tax return. You will need to visit the website of your state’s department of revenue to find the correct forms. When you file your state amended return, you will be required to attach a copy of your federal Form 1040-X as supporting documentation.