Who you are	Deadline to object
Individual or graduated rate estate	The later of one year after your filing due date for that return, or 90 days from the date on the notice
Corporation	90 days from the date on the notice
Trusts and most other cases	90 days from the date on the notice

Miss it and you can apply for an extension, but only within one year after the deadline passed, and only if you can show you intended to object and could not.

Three things worth knowing before you file anything:

An objection is often not the right tool. For a missing slip, a forgotten receipt or a simple arithmetic issue, a T1 adjustment request is faster and cheaper.
You generally do not have to pay while you object, if you are an individual or a regular corporation. Large corporations pay 50% up front.
Interest keeps running the whole time. If you lose, you owe interest on the entire period, and objections are currently taking 127 days at low complexity and 389 days at medium.

The date on the notice is the one that matters, not the day it arrived in your mailbox or landed in My Account. Take a photo of it. That date starts the clock.

Before You Object: Cheaper and Faster Alternatives

Most people who type “how to dispute a CRA assessment” do not actually need the formal dispute process. Filing an objection is a legal step, it goes to a different division inside CRA, and it takes months. Two lighter tools exist and both are usually faster.

A Simple Adjustment Request (T1 ADJ)

If the assessment is correct given the information CRA had, but the information was incomplete, you do not have a dispute. You have a correction.

Use a T1 adjustment request (form T1 ADJ, or the Change my return service in CRA My Account) when:

You forgot to claim a deduction or credit
A slip arrived after you filed
You made a data entry error, one of the common tax return mistakes to avoid in Canada
You have a receipt you did not submit

CRA can reassess a return this way for up to 10 years back for individuals. Turnaround is typically a few weeks online, versus months for an objection. There is no downside to trying this first, and if CRA denies the adjustment, your objection rights on the resulting notice are still there.

When an Objection Is Genuinely the Right Tool

Object when the disagreement is about law or facts, not paperwork:

CRA disallowed expenses it does not accept as business related, where the list of common tax deductions for small businesses in Canada is the place to start
CRA says you are a resident and you say you are not, a question decided by the Canadian tax residency rules
CRA reclassified a capital gain as business income, or a contractor as an employee under the employee vs contractor CRA rules
CRA denied a credit or exemption you believe you qualify for
CRA applied gross negligence penalties
An audit reassessment you disagree with in substance, which is a different animal from a desk review, as our comparison of a CRA audit vs a CRA review explains

Also object, even while you pursue something else, if the deadline is close. The objection preserves your rights. You can always settle it informally afterwards. You cannot revive a deadline that has passed.

Your situation	Best tool
Missing slip or receipt	T1 adjustment request
Arithmetic or data entry error	T1 adjustment request
Disagree with an audit’s conclusions	Notice of objection
Penalties and interest you want waived, but the tax is correct	Taxpayer relief request
Income you never reported and CRA has not found yet	Voluntary Disclosures Program
You owe the tax and cannot pay it	Payment arrangement, not a dispute

That last one matters. Objecting does not make a debt go away, it just pauses collection. If your real problem is cash flow rather than correctness, our guide to what to do when you cannot pay your CRA tax bill is the more useful place to start, and if collection has already begun, read whether CRA can freeze your bank account.

The Deadlines That Actually Apply

Individuals vs Corporations

For individuals, the deadline is generous and widely misunderstood. It is the later of:

One year after the filing due date for that tax year, or
90 days from the date of the notice of assessment or reassessment

So for the 2025 tax year, with a filing due date of April 30, 2026, you have until April 30, 2027 to object to your original assessment, even if the notice arrived in May 2026. The 90 day rule only becomes the binding one when CRA reassesses you later, well after the filing deadline has passed. If the underlying problem is that the return went in late, see the penalties for late filing of personal taxes in Canada.

For corporations, there is no one year alternative. It is 90 days from the date of the notice, full stop. Corporate reassessments therefore need a much faster response, and the notice frequently arrives while the person who needs to see it is away. The same urgency applies to a late corporate tax return and the CRA penalties that follow.

Applying Late: The One Year Extension Window

Missed the deadline? You can apply for an extension, but the bar is real. You have to show:

You could not object, or instruct someone to object for you, within the period
You intended to object
It would be just and equitable to grant the extension
You applied as soon as circumstances permitted

And you must apply no later than one year after the objection deadline expired. That outer limit is absolute. Once you are more than one year and 90 days past the notice date, the door is closed under this route entirely.

If CRA refuses the extension, you have 90 days to take that refusal to the Tax Court of Canada.

“I did not open the envelope” is not a reason. “I was in hospital for four months” is. Illness, absence from the country, a representative who failed to act, and CRA sending the notice to a stale address are the arguments that succeed.

Person reviewing financial documents before filing an objection

How to File a Notice of Objection

Three ways, and one of them is clearly better:

Method	Notes
My Account or My Business Account, Register my formal dispute	Fastest, timestamped, gives you a confirmation number. Use this
Form T400A by mail or fax	Works, but you are relying on postal dates for a deadline that matters
A signed letter setting out the facts and reasons	Perfectly valid. It just has to contain everything

Whatever route you take, include:

Your name, address and phone number
Your account or social insurance number
The tax year or years in dispute
The date on the notice you are objecting to
The specific issues, and the facts and reasons for each one
Supporting documents
Your representative’s details, if you have one

The single most important line: be specific about what you are disputing and why. “I disagree with the reassessment” is a valid objection but a weak one, and it invites a long clarification cycle. “CRA disallowed $18,400 of subcontractor costs on the basis that no invoices were provided. Invoices and bank records for all payments are attached at Tab 3” gets a real answer much sooner.

Organized case documents and folders on a wooden desk

Building Your Case

Facts, Documents and the Burden of Proof

Here is the part nobody enjoys hearing: in Canadian tax disputes, the burden of proof is generally on you, not on CRA. CRA’s assessment is presumed correct and it is your job to demolish the assumptions it rests on.

That reframes the whole exercise. You are not arguing that CRA cannot prove its case. You are proving yours. The preparation is the same work as an audit file, so our guide on how to prepare your books for a CRA audit is the checklist to work from.

What actually persuades an appeals officer:

Primary documents. Invoices, contracts, bank statements, cancelled cheques, logs. A spreadsheet you built last week is not evidence, it is a summary of evidence. Our guide to the record keeping requirements for CRA sets out what should have been kept in the first place.
A clean paper trail per issue. Organize by issue, not chronologically. Make it easy to say yes.
A short written narrative explaining what happened and why the treatment is correct, with references to the documents.
The law, where it helps. A relevant section of the Income Tax Act, a CRA interpretation bulletin, or a case on point carries real weight.

The Mistakes That Sink Objections

Arguing fairness instead of law. “This is unfair, I am a small business trying to survive” changes nothing in an objection. It might succeed in a taxpayer relief request, which is a different process.
Sending everything. Three banker’s boxes of unsorted receipts reads as “I have not organized my own case.” Send what proves the point.
Waiting for documents before filing. File on time with what you have and say more is coming. The deadline does not extend for document gathering.
Disputing everything in a reassessment. If four of six adjustments are actually correct, conceding them makes the two real issues far more credible.
Ignoring the interest. Objecting for 18 months and losing means 18 months of compounding interest on the full amount. If you can pay and might lose, paying and then objecting stops the interest while preserving every right you have.

Do You Have to Pay While You Object?

For most people, no. CRA normally postpones collection action on disputed amounts until 90 days after it issues its decision. You are not forced to pay while the objection is alive.

Two important qualifications.

Interest never stops. Collection stops, interest does not. At current prescribed rates, an amount in dispute for a year grows meaningfully. If you have the money and the case is genuinely uncertain, paying the disputed amount and then objecting is often the cheaper play, and our guide to strategies to avoid CRA penalties covers the rest of the avoidable costs. If you win, CRA refunds it with interest.

Some amounts are not paused at all, including payroll source deductions and GST/HST amounts held in trust. Those are trust funds, not your money, and CRA collects them during a dispute.

Why Large Corporations Still Owe 50%

A specific rule catches bigger companies. Large corporations, meaning those with taxable capital employed in Canada over $10 million, must pay 50% of the disputed amount when they file the objection. The collection pause does not fully apply to them.

Ordinary small and medium corporations are not in this category and get the normal hold. A similar 50% rule also applies to amounts in dispute involving charitable donation tax shelters.
Our other tax services:

What Happens After You File

Realistic Timelines by Complexity

CRA publishes its own averages, and they are sobering:

Complexity	Income tax objections	GST/HST objections
Low (straightforward, one clear issue)	about 127 days	about 115 days
Medium (multiple issues, some analysis)	about 389 days	about 303 days
High (large corporations, international)	over 690 days	over 500 days

CRA has also noted it is receiving higher than normal volumes, so treat these as optimistic. A medium complexity objection realistically takes more than a year, and there is very little you can do to speed it up.

Plan your cash flow accordingly. This is a long process and the interest clock is the reason to think hard about paying up front.

Possible Outcomes: Confirmed, Varied, Vacated

Outcome	What it means
Vacated	The assessment is cancelled. You win outright
Varied	Reassessed, partly in your favour. The most common result on multi issue objections
Confirmed	CRA stands by the original assessment. You now have 90 days to appeal

If you get a confirmation, that is not the end. It is the ticket to the next stage.

Courthouse exterior representing a tax appeal

If the Objection Fails: Tax Court of Canada

You have 90 days from the date CRA sends its decision to file a notice of appeal with the Tax Court of Canada.

There is also a rule people forget: if CRA has not decided your objection within 90 days of filing it, you can go straight to the Tax Court without waiting. Given the processing times above, that is a genuine option for a taxpayer who wants the matter moving, though in practice the appeals process at CRA settles most cases and going early is not always tactically smart.

The Court has two tracks:

	Informal procedure	General procedure
Limit	Federal tax and penalties in dispute of $25,000 or less per year, excluding interest, or a loss of $50,000 or less. GST appeals up to $50,000	Anything above those limits
Filing fee	None	$250, $400 or $550 depending on the amount
Representation	Yourself, a lawyer, or an agent such as your accountant	Yourself or a lawyer. Corporations must be represented by a lawyer
Formality	Simplified, designed to be navigable	Full rules of evidence and procedure

The informal procedure is genuinely accessible. No filing fee, your accountant can represent you, and the process is designed for people without counsel. For a disputed amount under $25,000 a year, it is a real option rather than a theoretical one.

Sitting on a reassessment you think is wrong? The most valuable thing we do at Maxpro Financials in these files is decide, early, which of the four routes actually fits: adjustment request, objection, taxpayer relief or payment arrangement. Choosing wrong costs months and sometimes the right to argue at all. Book a free initial consultation and bring the notice with you.

Objection vs Taxpayer Relief vs Voluntary Disclosure: Which Do You Need?

These three get confused constantly, and they solve different problems.

	Notice of objection	Taxpayer relief	Voluntary disclosure
What it disputes	The amount of tax assessed	Penalties and interest only	Nothing. It corrects your own past filings
When to use	You think the assessment is wrong	Tax is right, but circumstances beyond your control caused the penalty	You have unreported income or unfiled returns and CRA has not contacted you
Deadline	90 days or one year after filing due date	Within 10 calendar years of the year in question	Before CRA starts any enforcement action against you
Typical grounds	Facts and law	Illness, disaster, financial hardship, CRA error or delay	Voluntary, complete and involves a penalty
Form	T400A or online	RC4288	Application through the VDP

You can use more than one. It is common to object to the tax and, separately, request relief from the penalties if you lose. They run in parallel and neither prejudices the other.

The one that is genuinely time critical is the voluntary disclosure, and our guide on failing to report income to CRA covers what it involves. It is only available while the disclosure is still voluntary. Once CRA has contacted you about the issue, that door is shut permanently.
Our other financial services:

Frequently Asked Questions

Does filing an objection increase my audit risk?

No. Objections are handled by the Appeals division, which is separate from Audit and Collections, and separate again from the desk checks described in how CRA reviews small business returns. Exercising a statutory right is not a red flag, and there is no evidence it triggers future audits.

Can I object to interest and penalties only?

Not through an objection, which disputes the assessment of tax. If the tax is correct but you want the penalties and interest reduced, that is a taxpayer relief request on form RC4288, available for the 10 calendar years before the year you apply.

Do I need a lawyer or an accountant?

For the objection stage, an accountant is usually the right professional, and many objections are handled by taxpayers themselves. If you are not sure which you need, our comparison of a CPA vs a tax accountant in Canada helps, and what happens in an accountant consultation sets expectations for a first meeting. At the Tax Court, an accountant can represent you under the informal procedure, but the general procedure requires a lawyer for corporations and is strongly advisable for individuals.

What if I missed the 90 day deadline entirely?

Apply for an extension within one year of the deadline, showing you intended to object and could not. If you are past that window, look at a T1 adjustment request (up to 10 years for individuals) or a taxpayer relief request. Neither replaces objection rights, but both can still fix the outcome.

Is a notice of objection the same as an appeal?

No. The objection is an internal CRA review. An appeal is a court proceeding at the Tax Court of Canada, and it only becomes available after CRA confirms its assessment, or after 90 days of CRA silence on your objection.

How long do I have to object to a reassessment, not the original assessment?

The same rule applies, the later of 90 days from the reassessment notice or one year after the original filing due date. In practice, reassessments usually arrive years later, so the 90 day clock is the one that binds.

Can CRA reassess me for any year it wants?

Generally no. The normal reassessment period is three years from the date of the original notice of assessment for individuals and Canadian controlled private corporations, and four years for other corporations. Beyond that CRA needs to establish misrepresentation attributable to neglect, carelessness or wilful default, or you must have signed a waiver.

What if CRA is just not responding to my objection?

After 90 days from filing, you have the right to appeal directly to the Tax Court without waiting for a decision. That right alone sometimes gets a file moving when nothing else does.

Will I have to pay while the objection is pending?

For individuals and ordinary corporations, collection on the disputed amount is normally paused until 90 days after the decision. Interest keeps accruing. Source deductions and GST/HST held in trust are collected regardless.

Can I settle with CRA instead of going all the way?

Yes, and most files end this way. Appeals officers have authority to settle on a principled basis, meaning the settlement has to reflect a defensible view of the facts and law. Pure horse trading on the number is not permitted, but a well argued position on three of five issues very often produces a varied reassessment.

Disagree With CRA? Get It Reviewed First

The worst version of this situation is the one where someone spends eight months preparing a beautifully documented objection for an issue that a fifteen minute adjustment request would have fixed, or the one where someone waits for the perfect document bundle and files on day 94.

At Maxpro Financials we look at the notice, work out what CRA actually assessed and why, and tell you honestly whether you have a case worth making. Then we handle it: the objection or the adjustment, the document package, the correspondence, and the decision about whether paying up front is cheaper than the interest. It sits alongside our tax services in BC, our personal tax return filing service (T1) and our corporate tax return filing service (T2).

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How to Dispute a CRA Assessment | Notice of Objection Explained

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You Have 90 Days, and One Year Beyond That to Ask for an Extension