What if you realize you made a mistake on your tax returns months or years after filing? Don’t panic. Fortunately, the Internal Revenue Service offers time to file an amended tax return using Form 1040-X. Suppose you realize you didn’t claim the correct filing status, or you entered incorrect income, deductions, or tax credits—you can file an amended return up to 3 years after the date you filed the original (or within 2 years of paying the taxes owed . . . whichever is later).


Mistakes that Don’t Require an Amended Tax Return

Mathematical or Clerical Errors
If you made a simple mathematical or clerical error—not a mistake in claiming the wrong amount—the IRS would likely catch that mistake when processing your return. As a result, you may not have to file an amended return.

Missing Forms or Schedules
It’s also unnecessary to file an amended return if you forgot to attach a particular form or schedule to your tax return. The IRS will contact you by mail if they need additional information to fix these errors. However, you should file an amended return if an issue changes your filing status, income, deductions, or credits.


Reasons to File an Amended Tax Return

There are multiple reasons to amend your tax return, including:

  1. You received another W-2 or income statement after you filed your taxes
    Employers and businesses are required, by law, to send all income statements, like W-2s and 1099s, by January 31. However, sometimes that doesn’t happen. If you received a W-2 for a job that you held for only a few weeks or an interest statement for a long-forgotten bank account, even if the amount on the form is just a few hundred dollars, it could still affect your tax liability. The IRS expects you to report all of your income for the year. In this situation, it’s best to file an amended tax return.
  1. You didn’t claim a credit or deduction you were eligible to receive
    Several credits and above-the-line deductions (ones you don’t have to itemize to take) can help you lower your tax bill. For example, a health savings account (HSA contribution) or student loan interest. If you are eligible for one and don’t claim it, you could be leaving money on the table. Filing an amended tax return could allow you to claim that money.
  1. Your employer made a mistake on your W-2 and sent you a corrected document
    Sometimes people and companies make mistakes. If your employer made an error on your W-2, it would have to send you a corrected form. The new W-2C will display the previously reported information next to the correct information to let you know what needs to be updated. If the numbers changed and you already filed your return using the incorrect W-2, you must file an amendment.
  1. You forgot to report income from a side gig
    Suppose you worked a side gig but didn’t realize you had to report the extra income on your federal income tax return or forgot. The IRS will send you a CP2000 notice to inform you that the IRS’s information on file doesn’t match what you reported on your tax return. In this case, you may have underpaid your taxes. The notice shows the side gig income that you forgot to report. If the information in the CP2000 is correct, you don’t need to amend your return unless you have additional income, credits, or expenses to report. However, if you had expenses that needed to be deducted, you’ll need to file an amended return. To deduct your side-gig expenses, fill out a Schedule C for the side gig and file a 1040X. You will also want to write “CP2000” on top of your amended return, attach it to the response form, then mail it to the IRS.
  1. You used the wrong filing status
    What if you got married in November, but because you were single for most of the year, your spouse assumed you would have to file separate returns using a single filing status? The IRS considers you married for the entire year as long as you wed by December 31 of the tax year. In that case, you will need to file an amendment to change your filing status. And, considering the tax advantages of being married—such as a higher standard deduction—you may be eager to file that amended return.
  1. Your parents want to claim you as a dependent on their taxes, but you already claimed a personal exemption
    You filed your taxes before your parents did and claimed a personal exemption, but your parents wanted to claim you as a dependent on their taxes. When you did your taxes, you didn’t check the box on Form 1040 that says someone else could claim you as a dependent. Now your parents cannot claim you as a dependent on their taxes. If your parents are eligible to claim you on their taxes, and you agree they should, you’ll need to file an amendment.
  1. Someone else claimed your child on their tax return
    The IRS may reject your return if you and your ex (or someone else) have already claimed your child as a dependent. Only one of you can claim your child as a dependent to qualify for certain tax breaks like the child tax credit. For IRS purposes, the parent with whom the child lived for more than half the year and who provided more than half of the child’s support can claim the child tax credit. If you and your ex can agree that you should be the one to claim your child as a dependent, your ex will need to file an amended return to remove your child as a dependent. If the two of you can’t agree, the IRS will apply tie-breaker rules when deciding who will get to claim the child.

How Long Do You Have to Amend an Amended Tax Return?

Since the deadline to file your 2021 taxes this year was April 18, 2022, you have until April 18, 2025 to file an amended return if you realize you made an error. However, you can file amended returns for taxes filed in 2019 or later this year.


CWF Can Help with All Your Tax Needs!

If you need more information on filing an amended tax return, Campaign for Working Families (CWF) can help! If you’re a working family or an individual in Philadelphia, Montgomery County, or Southern New Jersey earning less than $65,000 per year, you can get free professional help at CWF. An IRS-certified CWF tax preparer will help you eliminate the stress of taxes and make sure you get the tax refund you deserve!