Filed a mistake on your tax return? How freelancers amend it (US, UK, Canada)

You filed, then found a wrong figure, a missing slip or a credit you skipped. Each country has a normal way to correct a return after filing — an amended return in the US, a Self Assessment correction in the UK, and Change my return or ReFILE in Canada. Here's what the IRS, HMRC and the CRA each say about when to correct, how to file the change, what happens to your bill, and when to get advice.

General information, not tax or legal advice. Not written or reviewed by a lawyer or an accountant. The short answer, the side-by-side summary, the when-to-amend table, the steps, the checklist and all the wording are ours; the official items come from the US, UK and Canadian government pages linked below. They are general rules for individuals, and none of them is a freelance law. US state amended returns, companies, GST/HST and VAT returns, payroll, Quebec and other countries were not checked. Official pages were read on 2026-10-18.

The short answer

1. Don't ignore a clear mistake on income, deductions, credits or tax owed — each agency explains how to correct a filed return.
2. Use the right route for your country: Form 1040-X (US), Self Assessment corrections (UK), or Change my return / ReFILE / Form T1-ADJ (Canada).
3. Watch the usual windows for refunds and online amendments; after those windows you may still write in or use mail.
4. If you owe more, pay when you can by the due date the agency names; if you can't, ask about paying over time.
5. Keep your records — the same invoices and receipts behind the original return.
6. A check or audit is different from you choosing to amend; see the related audit guide if the agency contacted you first.

On this page

• 1. When to amend vs leave it
• 2. United States: Form 1040-X
• 3. United Kingdom: correct a Self Assessment return
• 4. Canada: Change my return and ReFILE
• 5. Side by side
• 6. Step by step
• 7. Checklist
• Free tools and kits
• Where the sources differ
• When to get advice
• Related
• Sources

1. When to amend vs leave it

Our summary. Official wording is in the country sections below.

If the tax agency wrote to you first about a check, see tax audits and compliance checks rather than treating it only as an amendment you chose.

2. United States: Form 1040-X

• Start here: "If you find a mistake after filing your taxes, you may need to amend your return." "If you discover an error after filing your return, you may need to amend your return. The IRS may correct certain errors on a return and may accept returns without certain required forms or schedules. In these instances, there's no need to amend your return. However, file an amended return if there's a change in your filing status, income, deductions, credits, or tax liability." (IRS: File an amended return, page date 30-Sep-2026; IRS: Topic no. 308, page date 24-Sep-2026).
• When to file: "File an amended return if there's a change in your:"
  • Filing status
  • Income
  • Deductions
  • Credits
  • Dependents
  • Tax liability
• When you often don't: "You don't need to amend your return if we:"
  • Let you know that we corrected errors on your return.
  • Accept your return without certain forms or schedules or ask you to send them.
• What the form is for: "Use Form 1040-X, Amended U.S. Individual Income Tax Return to correct a previously filed Form 1040 series return or to change amounts previously adjusted by the IRS." "File Form 1040-X to:"
  • Correct Form 1040, 1040-SR, or 1040-NR (or older filings of Form 1040-A or 1040-EZ).
  • Make certain elections after the deadline.
  • Change amounts previously adjusted by the IRS.
  • Make a claim for a carryback due to a loss or unused credit.
  (IRS: About Form 1040-X, page date 19-May-2026).
• Refund timing: "Generally, to claim a refund, you must file an amended return within 3 years after the date you filed your original return or 2 years after the date you paid the tax, whichever is later. If you filed early, count from the April tax deadline." "To claim a refund, you must file Form 1040-X within 3 years after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later."
• More time in special cases: "You may have more time to amend for:"
  • A federally declared disaster
  • Service in a combat zone or contingency operation
  • A bad debt or worthless security
  • A foreign tax credit or deduction
  • A loss or credit carryback
• How to file: "To amend a return, file Form 1040-X, Amended U.S. Individual Income Tax Return. You can use tax software to electronically file your 1040-X online." "You can now file Form 1040-X electronically with tax filing software to amend your Form 1040, 1040-SR, or 1040-NR for the current or two prior tax periods." "Yes. If you need to amend your Form 1040, 1040-SR, 1040-NR, 1040-SS, or (prior to 2023) 1040-PR for the current or two prior tax periods, you can amend these forms electronically using available tax software products." "Paper filing is still an option for Form 1040-X." For e-file:
  • Submit a complete amended Form 1040, 1040-SR, or 1040-NR, with your changes, for the return year you are amending; and
  • Attach any supporting documents and new or changed forms and schedules.
  "An amended Form 1040, 1040-SR and 1040-NR return requires submission of all necessary forms and schedules as if it were the original submission, even if some forms have no adjustments. This is in addition to an attached Form 1040-X." "A new Form 8879 is required each time an amended Form 1040 or Form 1040-SR is electronically filed."
• How many: "You can file up to 3 amended returns for the same year." "You can electronically file up to three amended returns per tax year. If you file a third amended return that is accepted, all subsequent attempts will be rejected."
• Paper instead: "Amend your return on paper if either:"
  • earlier in the current year you filed the original return on paper and for a prior tax year
  • the return is for tax year 2021 or before.
  "Amended returns must be filed by paper for the following reasons:"
  • Any amended Form 1040, 1040-SR, 1040-NR, 1040-SS or (prior to 2023) 1040-PR returns older than the current or prior two tax periods cannot be amended electronically. Amended returns for those earlier tax years must be filed by paper.
  • If amending a prior year return originally filed on paper during the current processing year, then the amended return must also be filed on paper.
  (IRS: Amended return frequently asked questions, page date 02-Sep-2026).
• If you owe: "If you owe additional tax, and the due date for filing that tax return hasn't passed, you can avoid penalties and interest if you file Form 1040-X or a corrected return (Form 1040) and pay the tax by the filing due date for that year (without regard to any extension of time to file). This return will replace or supersede the original return." "If you owe additional tax, file your amended return, and pay the tax by the April due date to avoid penalties and interest. Your return will replace your original return. If you file after the April due date, don't include any interest or penalties on your amended return. We'll make any needed adjustments automatically." Mail payment with Form 1040-V when the IRS asks for a paper check with an amended return.
• Status: "You can check the status of your amended return with the Where's My Amended Return? tool. It may take up to 3 weeks for your amended return to show in our system." Use Where's My Amended Return?. "You should generally allow 8 to 12 weeks for your Form 1040-X to be processed. However, in some cases, processing could take up to 16 weeks."
• State returns: "If you change your federal return, it may affect your state tax liability. For information on how to correct your state tax return, contact your state tax agency. Don't attach your state tax return to your amended return."

Self-employment income and expenses are reported on Schedule C: see Schedule C for US freelancers. If you owe tax after amending and can't pay it all, see can't pay your tax bill?. State amended returns weren't checked in detail.

3. United Kingdom: correct a Self Assessment return

• What it is: "You can make a change to a tax return after you filed it, for example because you made a mistake." "Your bill will be updated based on what you report. You may have to pay more tax or be able to claim a refund."
• Usual window: "You can correct a tax return within 12 months of the Self Assessment deadline, online or by sending another paper return." "If you miss the deadline or if you need to make a change to a return from an earlier tax year, you’ll need to write to HMRC."
• Online: "You must wait 3 days (72 hours) after filing before updating your return." Then sign in, open Self Assessment tax return options, pick the tax year, correct and file again (GOV.UK: If you need to change your return, page date 2024-11-05).
• Paper: download or order the SA100, send the corrected pages, and "Write ‘amendment’ on each page and include your name and Unique Taxpayer Reference (UTR) - this is on previous tax returns or letters from HMRC."
• Software: "Contact the software provider for help correcting your tax return. Contact HMRC if your software is not able to make corrections."
• Your bill: "You’ll see your amended bill straight away if you updated your tax return online. Within 3 days, your statement will also show:"
  • the difference from the old one, so you can see whether you owe more or less tax
  • any interest
• After the window: "If your return is incorrect and it’s more than 12 months after the Self Assessment deadline you’ll need to write to HMRC to:"
  • report income you did not include in your tax return
  • claim overpayment relief, if you think you’ve overpaid tax
  "You can claim overpayment relief up to 4 years after the end of the tax year it relates to." For underpaid income, "You should contact HMRC in writing and include:"
  • the tax year you’re correcting
  • why you think you’ve paid too little tax
  • how much you think you’ve underpaid
  • your signature

Filing deadlines, late filing and late payment penalties, and the line about amending provisional figures, are in UK Self Assessment for freelancers — this page does not restate those amounts. Payments on account can change when your bill updates; see that guide's related links too.

4. Canada: Change my return and ReFILE

• What it is: "You may request changes to an assessed income tax and benefit return if you need to correct amounts or forgot to include information on your return."
• Wait first: "You must wait until you receive your notice of assessment (NOA) before you can request a change to your return. The return must have been filed by you or your tax preparer." "If you already submitted a request for changes, wait until you get a response from the Canada Revenue Agency (CRA) before requesting additional changes to the return."
• What you can change: "You can change your return if you need to adjust amounts or provide missing information, including:"
  • Reporting income (such as a T4 slip or tips)
  • Claiming a deduction, credit, or expense (such as childcare or medical costs)
  • Adding a missing tax slip (such as an RRSP contribution receipt)
• What this path is not for: "You cannot change a return to:"
  • Apply for benefits or credits
  • Make or revise an election
  • Allocate a refund to other CRA accounts
  • Update personal information, including:
  (CRA: How to change your return, page date 2026-09-29).
• Online: "Change your return with either your CRA account or certified tax software." The page shows "2 week processing time" for online and "19 week processing time" for mail.
• Change my return steps: "To make changes to your return:"
  • Sign in to your CRA account
  • Select Individual if you are changing your own return or Representative if you are changing someone else's
  • Select Tax returns
  • Find and select Change my return
  • Select the tax year you want to change and follow the steps
  • Save your confirmation number and summary of changes for your records
• ReFILE: "In certified tax software, look for the option to change your return using the "ReFILE" service. You do not need to use the same tax software you used to send your return, but it may be easier to use the same one. All certified software products now include the "ReFILE" service." "You must have used certified tax software to file the return you are requesting to change." "I understand and agree that I cannot change my name, address, marital status or direct deposit information on the return. This personal information is not transmitted with my return when I use ReFILE." "Once you send your ReFILE submission, a preliminary check of your changes will be performed. If your changes meet the basic requirements, the CRA will send you a confirmation number within seconds. This means that your ReFILE submission has been accepted for processing." (CRA: ReFILE Terms and Conditions, page date 2026-02-18).
• ReFILE limits: "You cannot use "ReFILE" to change:"
  • A return before the 2021 tax year
  • A bankruptcy return (or any year before the year of bankruptcy)
  • An optional T1 return for a deceased taxpayer
  • A return filed with the incorrect province or territory of residence
  • A return for an international or non-resident taxpayer, including deemed residents of Canada and individuals who left Canada during the year
  • A return where you have to complete Form T2203, for income from a business that has a permanent establishment outside your province or territory of residence
• Change my return limits: "You cannot use "Change my return" to change:"
  • A return for the 2015 tax year or earlier
  • A bankruptcy return (or any year before the year of bankruptcy)
  • An optional T1 return for a deceased taxpayer
  • A return filed with the incorrect province or territory of residence
  • Certain international and non-resident returns
• By mail: "Use the paper form and provide your supporting documents." "Complete Form T1-ADJ, T1 Adjustment Request" and send supporting documents to your tax centre.
• Old years: "A refund cannot be issued for adjustment request beyond 10 calendar years."

Canadian self-employment income and expenses go on Form T2125: see Form T2125 for Canadian freelancers. If a change leaves you owing and you can't pay at once, see can't pay your tax bill?.

5. Side by side

Our summary of sections two to four, not official wording.

6. Step by step

Our order of steps, based on sections two to four — not an official checklist.

1. Confirm what is wrong and which tax year it affects, using your filed return and your records.
2. Check whether the agency has already fixed it, or only needs a missing form.
3. In Canada, wait for your notice of assessment before requesting a change.
4. In the UK online, wait the short period GOV.UK requires after filing before you update.
5. Use the country’s own route: Form one-oh-four-oh-X, Self Assessment tax return options, or Change my return / ReFILE / Form T-one-ADJ.
6. Send every form and schedule the e-file path requires, even lines you did not change.
7. If you owe more, pay by the due date when you still can; if you can’t, ask about paying over time.
8. Save confirmation numbers, copies and the summary of what you changed.
9. Check status with the agency’s own tool after the wait it publishes.
10. If a federal change affects a state or provincial return, fix that return separately.

7. Checklist

Our summary of the official pages above, not an official checklist.

• Copy of the original return and any notices
• The corrected figures and which lines changed
• Supporting invoices, receipts and tax slips
• Software or paper form for the right tax year
• Bank details if you expect a refund by deposit
• A note of the confirmation or mailing date

For day-to-day records, see how to track freelance expenses. For when income counts, see cash vs accrual accounting.

Free tools and kits

• Our free invoice generator, receipt generator, expense and receipt log (Canada) and mileage logs for the US, the UK and Canada run in your browser; nothing you type is sent or saved. They help you keep records as you go; none of them files or amends a return for you.
• Our paid Freelance Billing Kit by Small Rows (US$12, one-time) keeps two lists that are useful when you check what you reported: the Invoices tab has each invoice's number, client, issue date, amount paid and paid date, and the Expenses tab logs the date, category, description and amount of each cost, with yearly totals by category. It doesn't file, amend, ReFILE, or contact the IRS, HMRC or the CRA for you.
• All three kits together: the All-Kits Bundle by Small Rows (US$24, one-time).

Where the sources differ

• Names: the IRS says amended return / Form 1040-X; GOV.UK says change or correct your return; the CRA says Change my return, ReFILE or Form T1-ADJ.
• Online windows: US e-file covers the current and two prior tax periods; the UK usual online window is twelve months from the Self Assessment deadline; Canada wants your notice of assessment first.
• After the window: the UK points to writing in (underpaid income or overpayment relief); the US has refund timing rules and special cases; Canada still offers mail for many situations, with a ten-year refund limit on the page we read.
• Personal details: ReFILE and Change my return are not the path to update name, address or direct deposit — the CRA says so on the pages we read.
• Old page dates: some pages show dates from earlier years (in Sources). We go by the wording on the day we checked.
• What we did not check: US state amended returns in detail; line-by-line Form 1040-X instructions; disaster and combat special timing beyond naming them; Making Tax Digital amend flows in detail; HMRC penalty rates for inaccuracies (see the audit guide); Revenu Québec; GST/HST and corporation returns; companies; the EU and other countries.

When to get advice

• the mistake involves fraud, a deliberate error or a large unexplained gap;
• you're past the usual amendment window and aren't sure which written claim to make;
• the change affects residency, bankruptcy, a deceased taxpayer return or multiple jurisdictions;
• you've already had a reassessment, a compliance check or an audit for the same year;
• you owe more after amending and can't see how to pay it;
• the return includes a company, GST/HST, VAT or payroll as well as your own self-employment lines.

Talk to an accountant or a tax adviser where you file. This page is general information only.

Related

• UK Self Assessment for freelancers
• Schedule C for US freelancers
• Form T2125 for Canadian freelancers
• Tax audits and compliance checks for freelancers
• Can't pay your tax bill? Payment plans for freelancers
• How to track freelance expenses

Sources

• United States: IRS: File an amended return (page date 30-Sep-2026) · IRS: About Form 1040-X (page date 19-May-2026) · IRS: Amended return frequently asked questions (page date 02-Sep-2026) · IRS: Topic no. 308, Amended returns (page date 24-Sep-2026)
• United Kingdom: GOV.UK: Self Assessment tax returns — If you need to change your return (page date 2024-11-05)
• Canada: CRA: How to change your return (page date 2026-09-29) · CRA: ReFILE Terms and Conditions (page date 2026-02-18)

Checked 2026-10-18. Found a mistake? Tell us via Support.