Filed your tax return and later realized something was wrong?

Maybe you forgot to include a tax slip, missed a deduction, entered an incorrect amount, or forgot to claim an eligible expense.

Don’t worry. In many situations, you can change your tax return after the CRA has assessed it.

You generally do not need to file an entirely new tax return. Instead, you can request an adjustment to the return you already filed.

When Should You Change Your Tax Return?

You may need to change your tax return if you discover that information was missing or incorrect.

Common examples include:

You forgot to report income, such as a T4 or other tax slip.
You forgot to include a tax slip.
You missed an eligible tax deduction.
You forgot to claim a tax credit.
You entered an incorrect amount.
You have additional eligible expenses that were not included on your original return.

The CRA says you generally need to wait until you receive your Notice of Assessment (NOA) before requesting a change.

If you have already submitted a request to change your return, you should wait for the CRA to respond before submitting another request.

How Can You Change Your Tax Return?

There are several ways to request an adjustment, depending on your situation.

1. Change Your Tax Return Online

For most situations, requesting a change online is the fastest option.

You can sign in to your CRA account and use the “Change my return” service.

The CRA currently lists an estimated processing time of about two weeks for online requests, although some requests can take longer if additional review is required.

You can also use ReFILE through eligible certified tax software if your original return was filed electronically.

2. Change Your Tax Return by Mail

If you cannot use an online option, you may be able to request the change by mail.

You generally need to complete Form T1-ADJ, T1 Adjustment Request and provide the required supporting documents.

The CRA’s current service page lists a longer processing time for mailed adjustment requests, so online is generally the better option when available.

3. Keep Your Supporting Documents

Keep your receipts, tax slips and other documents related to the change.

For example, if you are adding medical expenses that you forgot to claim, make sure you have the appropriate receipts and records available.

The CRA may ask for supporting documents after you submit your adjustment request.

What If You Forgot a Tax Deduction?

One of the most common reasons people want to change their tax return is because they discover a deduction or credit they missed.

Depending on your circumstances, this could include eligible medical expenses, childcare expenses, RRSP contributions, employment-related expenses or other tax credits.

Not every expense qualifies, so it is important to check the CRA rules before adding something to your return.

You can also read our guide on tax deductions Canadians often forget to claim to learn more.

Don’t File a Second Return for the Same Year

If you discover a mistake after filing, don’t simply file another tax return for the same year.

The CRA explains that you should wait for your Notice of Assessment and then request an adjustment to the return you already filed.

This helps avoid unnecessary confusion and allows the CRA to properly process the correction.

How Long Does It Take to Change Your Tax Return?

Processing times depend on how you submit your request and whether the CRA needs additional information.

Online requests are generally processed faster. The CRA currently lists approximately two weeks for online adjustment requests. Mailed requests take longer and may require additional processing time.

Some requests that require additional review can take considerably longer.

You can check the status of your request through your CRA account.

What If You Are Not Sure What to Change?

Tax returns can become complicated, especially when you are correcting information from a previous year.

If you are unsure whether something should be added, removed or changed, it is better to check before submitting an adjustment.

A mistake on an adjustment request can create additional delays or require another correction.

At Windsor Tax & Accounting Services, we can help you review your tax situation and determine what information may need to be corrected or added.

We can also help with other tax and bookkeeping needs, including personal tax preparation, small business bookkeeping, and HST-related services.

Need Help Changing Your Tax Return?

Making a correction after filing does not necessarily mean you have to start your tax return from scratch.

In many cases, you can change your tax return through the CRA’s online services and correct the information that was missed or entered incorrectly.

If you’re not sure what needs to be changed or how to make the adjustment, professional help can save you time and help you avoid additional mistakes.

Have a tax question?

Windsor Tax & Accounting Services
Serving Windsor, Ontario and surrounding areas
519-816-7318
info@windsortax.ca

This article provides general information and is not a substitute for professional tax advice.

Source: Canada Revenue Agency