- A T1 adjustment request (commonly made using CRA's online change-my-return service or Form T1-ADJ) is how you ask CRA to correct something on a return you've already filed — a missed…
- - You agree with CRA's assessment overall, but realize you left something off your original return.
Realizing you need to fix something on a previously filed tax return can lead to two very different paths, and the T1 adjustment vs objection decision is one most people have never had to make before. Pick the wrong one, and you can lose valuable appeal rights or waste time on a process that was never going to resolve your actual disagreement with the CRA.
The core distinction is simple once you see it: are you correcting your own return, or disputing CRA's assessment of it? The right tool depends entirely on which situation you're actually in.
The Core Difference
A T1 adjustment request (commonly made using CRA's online change-my-return service or Form T1-ADJ) is how you ask CRA to correct something on a return you've already filed — a missed deduction, an unclaimed credit, an income slip you forgot to include. It assumes you and CRA aren't in a dispute; you're simply fixing the numbers.
A Notice of Objection is the formal, legal mechanism for disputing a CRA assessment or reassessment you disagree with. It's an administrative step filed with the CRA's Appeals Branch, and it must happen before you can take a dispute to the Tax Court of Canada.
Side-by-Side Comparison
| T1 Adjustment Request | Notice of Objection | |
|---|---|---|
| Purpose | Correct your own filed return | Formally dispute a CRA assessment |
| Assumes a dispute exists? | No | Yes |
| Preserves right to appeal to Tax Court? | No | Yes |
| Typical use case | Forgot a deduction, credit, or slip | Disagree with CRA's reassessment |
| Deadline | CRA generally limits how far back adjustments can go — confirm the current window before you delay | For individuals and graduated rate estates: the later of one year after your filing-due date and 90 days after CRA sends the assessment notice (figures current as of mid-2026 — verify before relying on them); other taxpayers generally have 90 days from the notice date |
| Formality | Informal, often done online | Formal written submission to CRA Appeals |
When a T1 Adjustment Request Is the Right Tool
- You agree with CRA's assessment overall, but realize you left something off your original return.
- You want to add a receipt, slip, or credit you simply forgot to claim.
- There's no disagreement about how the law applies — just a correction to the numbers.
When a Notice of Objection Is the Right Tool
- CRA has reassessed you and you disagree with the result — for example, they denied a deduction you believe was valid.
- You want to preserve your right to eventually appeal to the Tax Court of Canada if CRA doesn't change its position.
- The dispute involves a genuine disagreement about the facts or how the law applies, not just a missing number.
What Happens If You Pick the Wrong One
Filing a T1 adjustment request when you actually disagree with CRA's assessment can waste time you didn't need to lose — an adjustment request doesn't extend or pause the objection deadline, and if CRA declines the adjustment or you remain unsatisfied, you may find your window to file a formal Notice of Objection has narrowed or closed. If there's any chance you'll want to preserve the right to escalate a disagreement, the safer route is generally to file the Notice of Objection within the applicable deadline, even while informal conversations with CRA continue.
Can You Switch From One to the Other?
If you've already filed a T1 adjustment request and then realize you actually disagree with how CRA is treating an item — rather than simply correcting an oversight — you can still file a Notice of Objection, provided you're within the applicable deadline. The reverse is less useful: if you've filed a Notice of Objection over a genuine dispute, there's generally no reason to also file an adjustment request for the same item, since the objection already covers it. When in doubt about which stage you're actually at, get advice before a deadline passes.
Frequently asked questions
Can I file both an adjustment request and a Notice of Objection?
They serve different purposes, so it's possible to need both over time — for example, an adjustment for an unrelated missed credit, and a separate objection for a specific reassessment you disagree with. They aren't interchangeable substitutes for each other, though.
What if I miss the Notice of Objection deadline?
A late-objection extension can be requested within a further limited window after the regular deadline passes, but it isn't guaranteed — the CRA (or ultimately the Tax Court) has to be satisfied the request meets the conditions for an extension. It's far safer to file on time.
Does a T1 adjustment request cost anything to file?
There's no filing fee to submit a T1 adjustment request through CRA's online service or by mail.
Will filing an objection trigger an audit?
Filing a Notice of Objection is simply exercising your right to dispute an assessment — it's a normal part of the tax system, not a red flag that invites broader scrutiny.
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