How to Change a Canadian Tax Return After Filing

First, wait for the notice of assessment

A notice of assessment is CRA’s response after it processes your filed return. CRA says you must receive it before you request a change. If you have already sent a change request for that return, wait for CRA’s response before asking for additional changes. That avoids treating an unanswered request as though CRA has already accepted it.

Keep the notice, a copy of the filed return, and the document that revealed the mistake together. For example, a tax slip may show income that was not included, or a receipt may support an amount you want CRA to reconsider. This guide explains the request process; it does not decide whether a particular deduction, credit, or expense belongs on your return.

What can a change request do?

CRA says you may request a change to amounts or missing information on an assessed income tax and benefit return. Its examples include reporting income, adjusting a deduction, credit or expense, and adding a missing tax slip such as an RRSP contribution receipt. Identify the tax year and the exact entry you want changed rather than sending a general message that the return is “wrong.”

Some tasks are not handled by changing the return. CRA says this service is not the route to apply for benefits or credits, make or revise an election, direct a refund to another CRA account, or update personal details such as address, direct deposit, marital status, or name. Use the separate CRA process for that task. If you are unsure which kind of request you have, start with the official “What you can change” section.

Three ways to request a change

CRA offers two online routes and a mail route, but not every return qualifies for every option. Its interactive selector asks about the tax year and situations such as bankruptcy, a deceased taxpayer’s return, an incorrect province of residence, and international or non-resident returns. Check that selector before choosing a route, especially if your return is not an ordinary recent personal return.

1. Change my return in your CRA account

For an eligible return, sign in to your CRA account, select Individual, then Tax returns and Change my return. Choose the year and follow the on-screen steps. Save the confirmation number and summary of changes when you finish. CRA says this route is available for most tax situations, subject to its listed restrictions.

“Change my return” cannot be used for a 2015 or earlier return. It also has restrictions for bankruptcy returns, optional returns for deceased taxpayers, returns filed with the wrong province or territory of residence, some international or non-resident returns, and a return requiring Form T2203 for certain out-of-province business income. The word “some” matters: CRA permits the service for certain international or non-resident situations and lists them on its page. Use the current selector rather than a broad rule of thumb.

2. ReFILE through certified tax software

If the return was originally filed using certified tax software, that software may offer CRA’s ReFILE service for an eligible year and situation. Look for its option to change a filed return. CRA says you do not have to use the very same product that filed the original return, although using it may be easier. Keep the submission confirmation and a copy of what changed.

ReFILE cannot change a return before the 2021 tax year. CRA also lists exclusions for bankruptcy, an optional return for a deceased taxpayer, the wrong province or territory of residence, certain international or non-resident returns, and returns requiring Form T2203 for qualifying out-of-province business income. The original return’s filing method and the person requesting the change also affect access. Check CRA’s full ReFILE conditions before treating it as available.

3. Mail Form T1-ADJ

If the online routes do not fit, CRA allows a paper request. Complete Form T1-ADJ, T1 Adjustment Request with the tax year, the entries and revised amounts, your identifying and contact details, and any authorization information that applies. CRA says to attach supporting documents for the entire amount, including amounts you previously claimed but did not already document, and send the package to your tax centre.

Send the change request separately from your current-year tax return. CRA’s form page offers a webform, accessible fillable PDF, printable PDF, large-print version and other formats. If you use the fillable PDF, CRA says to download it and open it in Acrobat Reader rather than trying to complete it inside a browser. Follow the current form instructions for the version you choose.

What about an older or unusual return?

The year alone does not settle every case. CRA’s text version lists which returns cannot use ReFILE or “Change my return,” and when mail is the available route. A return from 2015 or earlier, for example, cannot use “Change my return”; a return before 2021 cannot use ReFILE. For some special returns, paper is the only option, while some international situations can use the CRA-account route.

CRA says a refund cannot be issued for an adjustment request made more than 10 calendar years after the end of the tax year. Do not read that as a promise that every younger request will result in a refund—or as a simple ban on all older correspondence. The facts and CRA’s current rules for the particular year still matter. If your return concerns bankruptcy or someone who died, read the additional CRA instructions linked from the option selector before sending a form.

What to gather and keep

A short item-by-item record can make your request clearer. Keep the notice of assessment, the filed return, the tax year, the line or amount you want changed, what you believe the correct amount is, and the supporting document. If several entries are connected, identify each one so CRA can see which supporting document belongs with which request.

For illustration only, imagine you find a tax slip after receiving your assessment. The useful next step is to compare the slip with what your filed return reported, identify the affected entry, and use CRA’s option selector to find an eligible route. This example does not tell you what tax amount to enter or predict whether CRA will accept the requested change. Keep the online confirmation or a copy of the mailed package.

How long does CRA say it takes?

CRA currently lists processing times of within two weeks for an online request and within 16 weeks of receiving a mailed request. These are published service estimates, not guaranteed deadlines for an individual file. Multiple returns, an older tax year, a bankruptcy or deceased taxpayer’s return, a carryback, split-pension changes, or a request for more information can take up to 33 weeks; international and non-resident requests may take longer.

If you are waiting, use CRA’s current processing-time link and keep the confirmation you received. Do not send a second change request for the same return while the first is pending; CRA says to wait for its response.

What will CRA send back?

CRA reviews the request and then responds through online mail or letter mail, depending on your mail preferences and account setup. If it makes all requested changes, it issues a notice of reassessment showing the result. If it makes only some changes, the notice explains what it did not change, sometimes with a separate letter. If it makes no change, CRA sends a letter explaining why.

Read the response against the request you actually sent and keep both. A reader-initiated adjustment is not the same as formally disputing an assessment or reassessment. If the issue is that you disagree with CRA’s decision rather than that you omitted information from your own return, follow CRA’s separate dispute instructions; do not assume another T1-ADJ protects an objection deadline.