Your Guide to Fixing Tax Return Mistakes

What the Form Is For

Form 1040X is the IRS's official form for correcting mistakes on your federal income tax return. Think of it as an eraser for your tax return—it allows you to correct mistakes, add information you forgot, or make changes after you've already filed your original Form 1040, 1040A, 1040EZ, 1040NR, or 1040NR-EZ for the 2013 tax year. Unlike starting from scratch, Form 1040X shows the IRS exactly what you originally reported, what you're changing, and what the correct numbers should be—all in one transparent document. IRS Form 1040X Instructions

You might need Form 1040X if you discovered you forgot to claim a deduction or tax credit that could increase your refund, made math errors that affected your tax liability, received additional tax forms (like a W-2 or 1099) after filing, claimed the wrong filing status, forgot to report taxable income, or need to add or remove a dependent. The form essentially creates a new, corrected version of your tax return while showing the IRS your original work and the changes you're making.

However, not every mistake requires an amended return. The IRS automatically corrects basic math errors and will request missing forms or schedules directly. You usually don't need to file Form 1040X for simple math mistakes or forgotten attachments. IRS.gov - When to File an Amended Return

When You’d Use Form 1040X (Late/Amended)

For the 2013 tax year, you can generally file Form 1040X within 3 years after the date you filed your original 2013 return, or within 2 years after the date you actually paid the 2013 tax—whichever deadline comes later. If you filed your 2013 return early (say, in March 2014), the IRS considers it filed on the official deadline (April 15, 2014), so you'd count your three-year window from April 15, 2014, not your actual filing date. IRS.gov - Amended Returns & Form 1040X

However, if you had an extension and filed later than April 15, the IRS counts from your actual filing date. For example, if you had an October 15, 2014 extension but filed on July 1, 2014, your three-year window starts July 1, 2014. There are special situations with different deadlines: claims based on bad debt or worthless securities get 7 years, foreign tax credit or deduction changes get 10 years, and net operating loss or credit carrybacks generally must be filed within 3 years after the due date of the return for the tax year of the loss or unused credit (though you can use Form 1045 instead if filed within 1 year of the loss year). IRS Form 1040X Instructions 2013

Important timing note: You must wait until after you've filed your original 2013 return before submitting Form 1040X. Don't file a second original return or multiple copies—this delays processing. If you owe additional tax, the IRS charges interest from the original due date, even if you had an extension.

The time limit for filing Form 1040X can be suspended for certain people who are physically or mentally unable to manage their financial affairs. IRS Form 1040X Instructions 2013

Key Rules or Details for 2013

Several important rules governed Form 1040X for the 2013 tax year. First, the form could only be filed on paper—electronic filing wasn't available for amended returns in 2013. You must file a separate Form 1040X for each tax year you're correcting; you can't combine multiple years on one form. IRS Form 1040X 2013

The personal exemption amount for 2013 was $3,900 per person, which affects your calculations on the form. If your adjusted gross income exceeded certain thresholds ($300,000 for married filing jointly, $250,000 for head of household, $150,000 for single, $250,000 for qualifying widow(er)), your exemption deduction was reduced under phase-out rules. IRS Form 1040X Instructions 2013

For 2013, same-sex marriages were newly recognized for federal tax purposes. If you were legally married to someone of the same sex in a state or country that authorized such marriages, you could amend your 2013 return to change from single to married filing jointly or separately. The IRS did not require you to change your filing status on a prior return, even if you amended that return for another reason, but if you chose to amend, your return must be consistent with the filing status you selected. IRS Form 1040X Instructions 2013

You generally cannot change from a joint return to separate returns after the April 15 deadline has passed, but you can change from separate to joint returns using Form 1040X. Both spouses must sign the amended joint return, and both become jointly and severally liable for the full tax liability. When changing from separate to a joint return, both you and your spouse (or former spouse) have joint and several liability—meaning both of you are responsible for the tax and any interest or penalties due. IRS Form 1040X Instructions 2013

The processing time was typically 8–12 weeks, though complex amendments could take up to 16 weeks. You won't receive refund interest if an NOL refund is processed within 45 days of receipt. If you're claiming a refund exceeding the allowable amount, you face a potential 20% penalty on the disallowed portion unless you have a reasonable basis. IRS Form 1040X Instructions 2013

Step-by-Step (High Level)

Filing Form 1040X follows a logical sequence.

Step 1: Gather your materials.

Collect your original 2013 tax return (Form 1040, 1040A, or 1040EZ) with all schedules and worksheets, any IRS notices about adjustments to that return, the 2013 instructions for the form you originally filed, and any new tax documents (like corrected W-2s or 1099s) or supporting documentation for your changes. If you don't have the original instructions, you can order them by calling 1-800-TAX-FORM (1-800-829-3676) or find them online at IRS.gov/formspubs. IRS Form 1040X Instructions 2013

Step 2: Understand the three-column system.

Form 1040X uses three columns: Column A shows what you originally reported (or amounts previously adjusted by the IRS), Column B shows the net increase or decrease you're making, and Column C shows the correct amount after your changes. For example, if you originally reported $50,000 income but forgot $2,000, Column A shows $50,000, Column B shows +$2,000, and Column C shows $52,000.

Step 3: Complete the top section.

Check the calendar year box for 2013, enter your name, address, and Social Security number exactly as shown on your original return. If filing jointly, list names and SSNs in the same order. Check one filing status box—if you're changing status, check the new one. You must check one box even if you are not changing your filing status. IRS Form 1040X 2013

Step 4: Fill in the three-column section (lines 1–16).

Work through income, deductions, exemptions, tax, credits, other taxes, and payments. Only complete lines that are affected by your changes or that carry through from previous lines. When you change one line, it often affects several others (like changing income affects your AGI, which affects itemized deductions limits, which affects taxable income, which affects your tax). Many find the easiest way to figure the entries is to first make the changes in the margin of the return you are amending. IRS Form 1040X Instructions 2013

Step 5: Calculate your refund or balance due (lines 17–22).

Line 17 shows any overpayment from your original return. Line 18 compares your original and amended payment totals. Lines 19–22 determine whether you owe more tax or are due an additional refund.

Step 6: Complete Part I if changing exemptions.

If you're adding or removing dependents, show the original number, the change, and the correct number. List all dependents with their Social Security numbers and relationships. IRS Form 1040X 2013

Step 7: Write your explanation in Part III.

This is crucial—clearly explain every change you're making and why. Be specific: "Forgot to include Form 1099-INT from ABC Bank showing $350 in interest income" is better than "Additional income." Attach supporting documents like new W-2s, receipts, or corrected forms. IRS Form 1040X Instructions 2013

Step 8: Sign, date, attach documents, and mail.

Both spouses must sign joint returns. Attach any new or changed forms and schedules (like a new Schedule A if you're now itemizing). Make a copy for your records. Mail to the IRS Service Center listed in the instructions based on your state of residence or specific circumstances. Include payment if you owe additional tax. IRS Form 1040X Instructions 2013

Common Mistakes and How to Avoid Them

Mistake #1: Filing Form 1040X for errors the IRS automatically fixes.

The IRS corrects basic math errors and missing forms without your involvement. Don't file an amended return just because you forgot to attach a W-2 or made an addition mistake—the IRS will contact you if needed. Solution: Only amend if you're changing income, deductions, credits, filing status, or exemptions. The IRS will correct math errors while processing the tax return and notify you by mail. The agency will send a letter requesting any missing forms or schedules. IRS.gov - When to File an Amended Return

Mistake #2: Not using the three-column format correctly.

Many taxpayers confuse what goes in each column or forget to show negative numbers in parentheses. Solution: Column A always shows your original or previously adjusted figures. Column B shows only the change (the increase or decrease). Column C is the math: Column A plus or minus Column B. Use parentheses for losses, decreases, or negative amounts. IRS Form 1040X Instructions 2013

Mistake #3: Forgetting to attach supporting documentation.

If you claim a new deduction or credit, you must prove it. Solution: Attach copies (not originals) of new W-2s, 1099s, receipts, or schedules. If you received a corrected W-2c, attach it. If you're adding Schedule A for itemized deductions, attach the complete schedule. Do not attach items unless required to do so. IRS Form 1040X Instructions 2013

Mistake #4: Providing inadequate explanation in Part III.

Vague explanations like "Correction" or "Math error" frustrate IRS processors and delay processing. Solution: Write clear, specific explanations: "Received corrected Form W-2c from XYZ Corp showing additional $500 in box 1 wages and $75 in box 2 federal withholding not included on original return." If you need more space, attach a statement. IRS Form 1040X Instructions 2013

Mistake #5: Not adjusting related items.

Changing one number often creates a domino effect. For instance, if you increase your income, your AGI increases, which might reduce your itemized deductions due to AGI-based phase-outs, which changes your taxable income, which changes your tax and potentially your credits. Solution: Carefully review all AGI-dependent items: itemized deductions, certain credits (child tax credit, education credits), taxable Social Security benefits, and the exemption phase-out. A change you make to your AGI can cause other amounts to increase or decrease. If you change your AGI, refigure these items. IRS Form 1040X Instructions 2013

Mistake #6: Mailing to the wrong address.

The IRS has different processing centers for different situations. Solution: Check the "Where to File" section carefully. If you're responding to an IRS notice, mail to the address on the notice. If you received a hurricane grant or are filing Form 1040NR amendments, special addresses apply. IRS Form 1040X Instructions 2013

Mistake #7: Filing too early or too late.

Filing before your original return is processed causes confusion. Filing after the 3-year window loses your refund opportunity. Solution: Wait until your original return is fully processed. Track your deadlines carefully—for 2013 returns filed April 15, 2014, your deadline is generally April 15, 2017. To avoid delays, file Form 1040X only after you've filed your original return. IRS.gov - Amended Returns FAQ

What Happens After You File

Once you mail Form 1040X for your 2013 tax year, expect 8–12 weeks for processing, though complex cases can take up to 16 weeks. Unlike original returns, amended returns take longer because they require manual review by IRS personnel—they're not automatically processed by computer. IRS Form 1040X Instructions 2013

About three weeks after mailing, you can begin tracking your amended return's status using the IRS's "Where's My Amended Return?" tool at IRS.gov or by calling the toll-free number 1-866-464-2050. You'll need your Social Security number, date of birth, and ZIP code. The tool shows three stages: "Received" (the IRS got your Form 1040X and it is being processed), "Adjusted" (an adjustment was made to your account resulting in a refund, balance due, or no tax change), and "Completed" (your amended return has been processed and you will receive all information connected to its processing by mail). IRS.gov - Amended Return FAQs

If your amended return shows you're owed a refund, the IRS will process it and send your money via paper check (direct deposit was not available for 2013 amended returns filed on paper). You'll receive any refund from your original return separately and earlier than the additional refund from your amendment.

If you owe additional tax, pay when you file Form 1040X to minimize interest charges. The IRS charges interest from the original due date (April 15, 2014 for most 2013 returns) until the date you pay, even if you had an extension. If you don't pay within 21 days of the IRS's demand for payment (10 business days if you owe $100,000 or more), you'll face a late-payment penalty of 0.5% per month, up to 25% of the unpaid amount. IRS Form 1040X Instructions 2013

The IRS may contact you for clarification if your explanation in Part III is unclear or if they need additional documentation. Respond promptly to avoid further delays. Some amended returns take longer than 12 weeks for several reasons, including if the return has errors, is incomplete, isn't signed, is returned requesting more information, includes a Form 8379 (Injured Spouse Allocation), or needs routing to a specialized area or review by a revenue officer. IRS.gov - Amended Return FAQs

Keep copies of your Form 1040X and all supporting documents for at least three years from the date you filed the amended return, or two years from the date you paid the tax, whichever is later. This protects you if the IRS has questions or if you need to amend again.

FAQs

Q1: Can I e-file Form 1040X for my 2013 tax return?

No. For the 2013 tax year, Form 1040X could only be filed on paper by mail. Electronic filing for amended returns wasn't available until later tax years. You must print Form 1040X, complete it by hand or type on it, sign it, and mail it to the appropriate IRS Service Center. IRS Form 1040X Instructions 2013

Q2: Do I need to amend my state tax return if I'm amending my federal return?

Probably, yes. If you are filing Form 1040X to carry back your unused foreign tax credit, follow special carryback procedures. Most states base their calculations on your federal adjusted gross income or taxable income. Check with your state's department of revenue for specific requirements and deadlines. IRS Form 1040X Instructions 2013

Q3: What if I already received my refund from my original 2013 return but now need to amend?

You can still file Form 1040X. If your amendment shows you owe more tax, you'll need to pay the difference plus interest from the original due date. If your amendment shows you're owed an additional refund, enter your original refund amount on line 17, and the IRS will send you only the difference between the original and amended refund amounts. IRS Form 1040X 2013

Q4: How many times can I amend the same tax year?

There's no stated limit, but each time you file Form 1040X, use your most recently adjusted figures in Column A (either from your previous amendment or from IRS adjustments). File a separate Form 1040X for each year you are amending. Don't file more than one original return for the same year, even if you haven't received your refund or haven't heard from the IRS since you filed—this could delay your refund. IRS Form 1040X Instructions 2013

Q5: Will amending my return trigger an audit?

Filing Form 1040X causes the IRS to review your return. As long as your amendment is accurate, well-documented, and clearly explained, you're correcting your tax obligations properly. Use the Interactive Tax Assistant tool "Should I File an Amended Return?" on IRS.gov to help decide if you should file an amended return. IRS.gov - Should I File an Amended Return

Q6: What if I miss the 3-year deadline to amend my 2013 return?

Unfortunately, if you miss the deadline (generally April 15, 2017 for 2013 returns), you cannot claim a refund. The IRS won't process refund claims after the statute of limitations expires. However, if you're amending to pay additional tax you owe, you should still file—the IRS will always accept payment of taxes owed, regardless of timing. IRS.gov - Amended Returns

Q7: Can I still get the same-sex marriage filing status change for my 2013 return?

If you're within the statute of limitations (generally three years from when you filed your original 2013 return), yes. The IRS announced in 2013 that same-sex couples legally married in any state or country would be recognized as married for federal tax purposes. You can amend to change from single to married filing jointly or separately, but you're not required to change your filing status on a prior return even if you amend for another reason. IRS Form 1040X Instructions 2013

Notes

Note: This summary is based on official IRS Form 1040X instructions and guidance for the 2013 tax year. Tax laws change, and individual circumstances vary. For complex situations, consult with a qualified tax professional or contact the IRS directly at 1-800-829-1040. IRS.gov Forms and Publications

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