Form 1040X Instructions – How to File an Amended Tax Return


1040x tax form

If you finished your tax return and mailed it in by the tax filing deadline, but later discovered you made a mistake, don’t fret. You can still adjust your return.

Essentially, the IRS allows a “do-over” on your taxes in case you make an error or omission. By utilizing Form 1040X, you can fix any mistakes you spot after your initial tax filing – and you may have more time to do so than you think. You can file a 1040X within three years of your original filing, and amend details on your filing status, number of dependents, total income, tax deductions, or tax credits.

What Is Form 1040X?

The 1040X is the form you use to amend or change your tax return up to three years after you filed it (or up to two years within the date you paid any taxes owed, whichever is later). You can use 1040X to correct any of the 1040 tax forms, including 1040A, 1040EZ, 1040NR, and 1040NR-EZ. If a mistake on a related form (such as Schedule A) caused the error, redo that form and include it when you file the 1040X.

The 1040X is a simple two-page form that must be filed on paper, not e-filed. To fill it out, start by checking the box to show the tax year that you are amending. (Note: If you are filing an amended return for more than one year, you need a separate 1040X for each return, and they must be mailed in separate envelopes to the appropriate IRS processing center.)

The form has three columns along the right-hand side. Column A shows figures from the original return, Column B shows the net change you are making – either increase or decrease – and Column C shows the corrected figures. There is also an area on the second page of the form where you should go into more detail about the specific changes and the reasons for those changes.

If you’re expecting a refund from your original tax return, don’t file your amended return until after you have received that refund. You can go ahead and cash the refund check from your original return, and the IRS then sends you any additional refund you are owed. Likewise, if you expect to owe additional tax after filing your amended return, you should pay the tax as soon as possible to limit any interest and penalty charges.

Essentially, Form 1040X asks about changes you need to make to your adjusted gross income, deductions, tax liability, and any exemptions you may have had. The form also contains a section for “explanation of changes,” as anyone filing the form must state why an error was made. There is one downside: If you’re owed a refund due to the changes you make, you might not get it as quickly as you hoped. Because every form is reviewed by an individual, it can take up to three months to process.

How to Complete Form 1040X

Each line on the form requires that you input values into three columns:

  • Column A: The original value as it appears on your original tax return (or, if you’ve already amended it, from your last 1040X)
  • Column B: The amount that the value has increased or reduced due to your changes
  • Column C: The actual corrected value

Unless you’re making multiple changes, most of the values in Column A are simply copied over to Column C, yielding a change of zero. Many people find the easiest way to figure the entries for Form 1040X is to first make the changes in the margins of the return they are amending.

1040x tax form

Let’s look at each section of the 1040X individually:

Filing Status

Just above the “Income and Deductions” section is a section on Filing Status. You can change your filing status – single, head of household, qualifying widow – by filing an amended return. You cannot change your status from married filing jointly to married filing separately after you’ve already filed your taxes, but you can change any other status.

Healthcare Coverage

In the last year, you may have seen a new section on healthcare coverage pop up, just to the left of the “Filing Status” section, entitled “Full-year coverage.” This section asks whether all members of your household had “full-year minimal essential health care coverage.”

If you cannot check “Yes” and do not qualify for a healthcare coverage exemption, you may owe a shared responsibility payment. If you’re unsure, see Form 8965, Health Coverage Exemptions, to determine if anyone in your household qualifies for a coverage exemption.

If you made any changes on Form 1040X, lines 1 through 5, you may need to refigure your individual shared responsibility payment. Note: The shared responsibility payment does not apply to tax years before 2014, and you don’t owe a shared responsibility payment if you can be claimed as a dependent by another taxpayer.

Income and Deductions

While this form may seem intimidating – especially because you probably find yourself filling it out due to a mistake – it’s really just a matter of simple addition or subtraction. Remember, in column A, you just enter the amounts from your original return. In Column B, you enter the increase or decrease necessary to correct the form, and in Column C, simply show the accurate (amended) numbers. For numbers that don’t need to be changed, just leave the field blank. Although it may be tempting to fill in all the line items to be thorough, if it was correct on the original form, there’s no need to “correct” it here.

Here’s a look at all the line items you may need to fill in to complete your form:

  1. Adjusted Gross Income. Add or subtract any income or above-the-line deductions you need to change, and then you can recalculate your adjusted gross income. So you don’t get confused, redo your original 1040 in order to have an accurate reference point before filling out the 1040X. If you’ve used or changed any schedules in the process (such as Schedules B, C, or D), include those with your amended return.
  2. Itemized Deductions or Standard Deduction. Determine any changes in your standard deductions or itemized deductions, and input the new number on this line. Remember that itemized deductions are deductions for certain expenses that are listed on Schedule A (Form 1040). Include a new Schedule A with your 1040X if you need to amend that form.
  3. Subtract Your Itemized or Standard Deduction From Your Adjusted Gross Income.
  4. Exemptions. If you’re changing any exemptions, you need to complete Part 1 of the form (on the second page) to explain your position precisely.
  5. Subtract Your Total Exemptions (Line 4) From Your Adjusted Gross Income (Line 3) and You Have Your Taxable Income.

Tax Liability

  1. Tax and Method Used to Figure Tax. It is recommended that you use IRS-provided tax tables.
  2. Credits. (Earned Income Tax Credit, Child and Dependent Credit, educational credit, etc.)
  3. Subtract Your Credits (Line 7) From Your Tax (Line 6).
  4. Healthcare: Individual Responsibility. See instructions for line 61 of Form 1040.
  5. Other Taxes. This section refers to self-employment tax, unreported Social Security and Medicare Tax, additional IRA tax, or advance EIC payments.
  6. Total Tax. This is all the tax you owe, minus your credits.


  1. Federal Income Tax and Other Taxes Already Withheld. This includes anything you’ve already had withheld, plus any amounts you might not have included the first time around.
  2. Estimated Tax Payments. Enter the estimated tax payments you claimed on your original return, and include any of your prior year’s overpayment that you elected to apply to the year you’re amending.
  3. Earned Income Credit. If you are amending your return to claim the EIC and you have a qualifying child, attach Schedule EIC (Form 1040A or 1040).
  4. Refundable Credits. There are many refundable credits that you can input here, including those covered by forms 8812 (child tax credit), 8863 (education credits), 8885 (health coverage tax credit), 8962 (premium tax credit), and more. If you didn’t complete one of these forms when you first filed taxes, now you can.
  5. Any Taxes You Already Paid With Your Original Filing or Prior 1040X. Total amount paid with request for extension of time to file, tax paid with original return, and additional tax paid after return was filed.
  6. Total Payments. Lines 12 through 16 added up. These are the amounts that offset your tax liability.

Refund or Amount You Owe

  1. If you’ve overpaid, meaning you have a refund due to you now that you’ve amended your original return, enter that amount here.
  2. Subtract that refund (line 18), if any, from your total tax payments (line 17).
  3. If the amount in line 19 is less than the amount in line 11 (in Column C), you have to pay an additional tax as a result of filing this amended return. If so, enter the amount here.
  4. If the amount in line 19 is greater than the amount in line 11, you will receive a tax refund. If this is the case, enter the amount here.
  5. If you are due a refund and want it sent to you, enter the amount here that you would like to be refunded.
  6. If you’d rather apply this refund to your tax liability as an estimated tax payment, you can do that too. This means that the IRS holds onto the money for you, and you can use it as a credit on your next tax return.

1040X Part I: Exemptions

If you’re changing the number of exemptions you claim, you also have to fill out Part I of the 1040X to explain why you are making that change, and then break it down among the types of dependents in lines 24 through 27. List all your dependents and their Social Security numbers and relationships to you, and whether they qualify for the child tax credit. If you aren’t making changes to your exemptions, you can completely ignore Part I.

Explanation of Changes

Here’s the fun part – this is where you get to explain why you need to amend the return. Keep it short, simple, and to the point. If you changed any forms other than your 1040, you need to include copies of the latest versions, and explain where you made changes and why.

If you had one change to make, your explanation should be easy enough. For example, you could say something as short and simple as, “I forgot to include tips from my part-time job.” However, if you made several mistakes – perhaps with a stray 1099 you missed, as well as student loan interest, it may be best to break down your explanation line-by-line. For example, you could write, “Per line 9, I failed to take my student loan deduction. And per line 3, I failed to include income from a 1099 that was delayed.”

Assembling Your Return

Assemble any schedules and forms behind Form 1040X in order of the “Attachment Sequence No.” shown in the upper-right corner of the schedule or form. If you have supporting statements, arrange them in the same order as the schedules or forms they support and attach them last. Do not attach a copy of your original return, correspondence, or other items unless you are required to do so.

Final Word

The IRS lets you amend a return within three years from the date you originally filed it, or within two years of the date you paid any taxes owed, whichever is later. So, if you think you missed something, you have nothing to lose by checking. If you find that you do need to make changes, it’s relatively easy to fill out Form 1040X and send it in.

Have you ever filed an amended return? Did you receive a refund, or did you end up owing more money as a result?

  • harold doglus

    Hi, Kira:
    Thanks very much for your post that I urgently needed. I accidentally forgot to include my W-2 withholding on my 2011 tax return. As the result, I paid $1784 tax as I was supposed to have a $315 refund. I still have a few more questions about 1040x:
    1. Do I need to fill line 12-15 to arrive to line 16 total payment and subtract it from my total tax (line 10) if I don’t have other amend in the “Payments” section? I did have another payment deduction on my original tax return.
    2. To my understanding, I only need to fill out line 20-21 with a total amount of $2099 ($1784+315) because I didn’t have a tax refund. Am I correct? Thanks very much.


    • Kira Botkin

      If you don’t have anything to put in a line, 0 is an acceptable answer. But don’t send the IRS a form with only lines 20 and 21 filled out. You should fill in any lines for which you have an answer.

  • cartweet

    Hi kira:
    I need to file a 1040x because I forgot to fill out the dependent care section and missed a good chunk of refund. Is there anything else I need to include with the 1040x when I mail it out if this is my only change?

  • Frank

    My full time student son claimed himself as a deduction for tax year 2014 (earned $4090 during summer job). Can he file a 1040X, amend his return so I can claim him as a deduction/?

  • Sky

    Hi Kira,

    Thanks for your blog. I need help on filling out 1040X 2015 for amending the missing 8962 form that now I have completed.

    The only change I am making is Line 15 (Refundable credits from: 8962(x) on 1040X. There is 1500 from Line 26 of 8962 form that I suppose goes on column B and C on 1040X.

    How do I fill out column C from Line 12 of 1040X since there is no change in Federal income tax withheld?


  • rk50

    I neglected to answer Line 61 on my Form 1040. That is the only change I am making on my 1040X. I’m retired and have health care through my former employer. The instructions I read said,

    “You are providing only additional information. If you are not changing any dollar amounts you originally reported, but are sending in only additional information, do the following.
    Check the box for the calendar year or enter the other
    calendar or fiscal year you are amending.
    Complete name, current address, and SSN.
    Check a box in Part II, if applicable, for the Presidential
    Election Campaign Fund.
    Complete Part III, Explanation of changes.”

    So that is all I did. Was I wrong?