What is a CRA notice of reassessment?

A document the CRA issues after reviewing a filed tax return and adjusting the result. It can change refunds owed, balances owing, interest, and penalties.

How long does CRA have to reassess my tax return?

Three years for individuals and most CCPCs, four years for non-CCPC and large corporations, six years for foreign-related items, and unlimited time when CRA establishes misrepresentation due to neglect, carelessness, wilful default, or fraud.

What is the deadline to dispute a CRA reassessment?

90 days from the date on the notice. You file a Notice of Objection, typically using Form T400A or through CRA My Account.

Should I pay before objecting?

Generally yes for individuals. Interest continues to accrue during an objection at the prescribed rate (9 percent in Q2 2026). Paying preserves cash flow and the amount is refunded with interest if you win.

Why did CRA reassess if I already got a notice of assessment?

The original notice of assessment is provisional. CRA can later add missed slips, disallow deductions on review, or adjust based on audit findings, within the normal reassessment period.

Does CRA charge interest on amounts I dispute?

Yes. Interest accrues at the prescribed rate (9 percent in Q2 2026) until the balance is paid. The rate is set quarterly and applies whether or not you have an active objection.

Can CRA reassess more than once in a year?

Yes. If new information surfaces or a different audit area is reviewed, CRA can issue multiple reassessments for the same tax year, each with its own 90-day objection window.

CRA Notice of Reassessment: What It Means and How to Respond

A CRA notice of reassessment changes a previously filed return, often months or years later. The most important deadline is the 90-day window to file a Notice of Objection. CRA's normal reassessment period is three years for individuals and most CCPCs, with longer periods for corporations and unlimited time when misrepresentation is established.

Reviewed by Canadian Money Help Editorial Updated May 4, 2026 Source CRA

A CRA notice of reassessment is a document the Canada Revenue Agency issues after reviewing a previously filed tax return and changing the result. It can come months or years after the original assessment, and it can either reduce a refund, demand a balance owing, or trigger interest and penalties. The most important deadline on the notice is the 90-day window to file a Notice of Objection, which preserves your right to appeal. Paying the amount owing does not waive your right to object.

Why CRA reassesses

Reason	Detail
Slip matching	CRA matches T4, T5, T3, T4A, RRSP and tuition slips to your return. A missing slip triggers an automatic reassessment.
Pre-assessment review	CRA asks for receipts (medical, donations, child care, business expenses). If you do not respond or the receipts do not support the claim, CRA disallows the deduction.
Post-assessment review	Same as above but issued months after the original notice of assessment, typically July to December.
Audit findings	Full audits result in formal reassessments adjusting business income, GST/HST, payroll, or other items.
Voluntary adjustment	You filed a T1-ADJ to correct a prior return; CRA reassesses to apply the change.
Trust assessment (e.g., TFSA carrying on a business)	CRA assesses the TFSA trust under paragraph 146(4)(b); the holder receives the notice as trustee.

How long CRA has to reassess

Type of taxpayer	Normal reassessment period
Individuals and most CCPCs	Three years from the date of the original notice of assessment
Non-CCPC corporations and most large corporations	Four years from the date of the original notice of assessment
Trust returns	Three years
Any taxpayer, when CRA establishes misrepresentation due to neglect, carelessness, wilful default, or fraud	Unlimited
Foreign-related transactions and Specified Foreign Property	Six years (extended period under ITA 152(4)(b.2))

What the notice contains

Tax year being reassessed.
Original assessment figures versus reassessed figures.
The specific changes (e.g., disallowed medical expenses, added T4 slip).
New balance owing or refund amount.
Interest accrued, calculated daily from the original filing deadline.
Any penalties (gross negligence, late-filing, repeated failure, T1135, etc.).
The 90-day deadline to file a Notice of Objection.

Five-step response checklist

Read the notice and identify which lines changed and why. Compare against your filed return.
Pull together supporting documents for the disputed items: receipts, contracts, slips.
If the change is minor and clearly correct, accept and pay. CRA charges interest on unpaid balances at the prescribed rate, currently 9 percent on overdue tax (Q2 2026).
If you disagree, decide between: (a) phoning CRA to request an adjustment if there is a clear error; (b) filing a Notice of Objection on Form T400A within 90 days; or (c) using the Voluntary Disclosures Program if undisclosed income is involved.
Keep paying any amount owing while disputing. Interest continues to accrue during an objection. Paying the disputed amount and getting it refunded if you win the objection is often cheaper than letting interest pile up.

Worked example: missing T4 slip

A taxpayer filed her 2024 return in March 2025 reporting employment income of $58,000 from a single T4. In November 2025, CRA reassesses to add a $3,200 T4 from a side gig that the taxpayer forgot. The reassessment shows additional federal tax of $448 (14 percent) plus Ontario tax of $162 (5.05 percent), plus interest of $35, plus the repeated-failure penalty of 10 percent of the unreported amount ($320) since this is the second time in three years she missed a slip. Total: $965.

Her options: (1) accept and pay; (2) object only to the repeated-failure penalty if she has a reasonable explanation; (3) request taxpayer relief on the penalty. Filing a T400A within 90 days preserves her appeal right while she gathers the explanation.

Interest rates that apply

CRA’s prescribed interest rate adjusts quarterly. As of Q2 2026, the rate on overdue taxes is 9 percent annual, compounded daily. The rate on refunds owed by CRA to individuals is 7 percent (lower than the overdue rate, by design). These rates change every January, April, July, and October.

Cross-references

Frequently asked questions

What is a CRA notice of reassessment?: A document the CRA issues after reviewing a filed tax return and adjusting the result. It can change refunds owed, balances owing, interest, and penalties.
How long does CRA have to reassess my tax return?: Three years for individuals and most CCPCs, four years for non-CCPC and large corporations, six years for foreign-related items, and unlimited time when CRA establishes misrepresentation due to neglect, carelessness, wilful default, or fraud.
What is the deadline to dispute a CRA reassessment?: 90 days from the date on the notice. You file a Notice of Objection, typically using Form T400A or through CRA My Account.
Should I pay before objecting?: Generally yes for individuals. Interest continues to accrue during an objection at the prescribed rate (9 percent in Q2 2026). Paying preserves cash flow and the amount is refunded with interest if you win.
Why did CRA reassess if I already got a notice of assessment?: The original notice of assessment is provisional. CRA can later add missed slips, disallow deductions on review, or adjust based on audit findings, within the normal reassessment period.
Does CRA charge interest on amounts I dispute?: Yes. Interest accrues at the prescribed rate (9 percent in Q2 2026) until the balance is paid. The rate is set quarterly and applies whether or not you have an active objection.
Can CRA reassess more than once in a year?: Yes. If new information surfaces or a different audit area is reviewed, CRA can issue multiple reassessments for the same tax year, each with its own 90-day objection window.