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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →For Canadian federal income tax, an assessment is the Canada Revenue Agency’s (CRA’s) determination of your tax, interest, and penalties for a year. A reassessment is a later determination for that same year. A reassessment can increase your balance, reduce it, or leave the assessed amounts unchanged; it does not automatically mean you owe more.
The CRA’s time to reassess and your time to challenge a notice are separate clocks. The general reassessment period is usually three or four years, depending on the taxpayer category, while objection deadlines are commonly 90 days or the later of one year after the filing deadline and 90 days after the notice for many individuals. The exact rule depends on the notice, tax year, taxpayer type, and issue. This article covers Canadian federal income tax; other jurisdictions, including the United States, use different procedures.
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Assessment and reassessment: the legal difference
When CRA processes an income-tax return, it determines the amount of tax, interest, and penalties for that year and issues a notice. That determination is an assessment. The notice may show a refund, a balance owing, or no tax payable.
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CRA distinguishes a notice stating that no tax is payable from an assessment in law. The notice still communicates CRA’s processing result, but the statutory concept of an assessment is tied to a determination of tax, interest, or penalties. Read the wording and date on the document rather than assuming every CRA letter starts the same deadlines.
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A reassessment is a later determination for the same tax year. CRA can issue one after processing a taxpayer-requested change, reviewing information, auditing, or taking another authorized action. It may replace the earlier amount, reduce it, increase it, or confirm the same amounts. CRA says a notice stating any amount of tax, interest, or penalties owing is an assessment or reassessment even when the amounts have not changed.
| Point | Assessment | Reassessment |
|---|---|---|
| Timing | The original determination after CRA processes the return. | A later determination for the same tax year. |
| Amount | May show a refund, balance owing, or no tax payable. | May increase, reduce, or leave the prior tax, interest, or penalties unchanged. |
| Typical trigger | Processing of the filed return and information available at that time. | A taxpayer-requested adjustment, review, audit, or other authorized CRA action. The specific reason should be in the notice or CRA explanation. |
| Challenge | Generally can be challenged by filing a notice of objection within the applicable statutory deadline. | Generally can be challenged in the same way, subject to notice-specific rules and deadlines. |
CRA’s guide, Resolving your dispute: Objection rights under the Income Tax Act, explains the objection and appeal framework. If a notice is unclear, you can ask CRA for an explanation, but that conversation does not replace the deadline for filing a formal objection.
How an original assessment becomes a reassessment
The sequence is usually straightforward:
- You file a return. You report income, deductions, credits, and other required information for a tax year.
- CRA processes the return. It calculates the result and sends a notice of assessment or, where applicable, a notification that no tax is payable.
- Something prompts a later review or change. You may ask CRA to change a filed return, or CRA may review information, conduct an audit, or identify an issue through another authorized process.
- CRA issues a later determination. The notice of reassessment states the revised tax, interest, and penalties, and usually gives a reason or identifies the item changed.
The word “reassessment” describes the later timing, not the direction of the change. For example, correcting an omitted deduction could reduce tax, while disallowing a credit could increase it. CRA can also issue a reassessment that confirms the prior amount.
Why CRA may reassess a return
A notice can arise from several situations, and the label alone does not tell you which one occurred. Common categories include:
- Taxpayer-requested adjustment: You ask CRA to change a previously filed return. CRA reviews the request and may issue a reassessment, partially accept it, reject it, or make no change.
- Review of supporting information: CRA may ask for receipts, schedules, or explanations and then change an item after considering the response.
- Audit: CRA examines books, records, or transactions in more detail and reassesses if it finds an adjustment.
- Information received from another source: A discrepancy between your return and information slips or other data can lead to a later determination.
- Correction of a processing issue: CRA may correct an error or apply information that was unavailable when the original notice was issued.
These are categories, not conclusions about your case. The exact reason, tax line, and amount must come from your notice, the attached explanation, or your CRA file. If the explanation is incomplete, request clarification promptly while preserving your objection deadline.
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CRA’s normal reassessment period: three or four years, with exceptions
The normal reassessment period is the time in which CRA may generally reassess a return. It is not the time you have to object. CRA guidance describes these general periods:
| Taxpayer category | General normal reassessment period | Qualification |
|---|---|---|
| Individuals, trusts other than mutual fund trusts, and Canadian-controlled private corporations | Generally three years | Measured using the relevant original assessment or no-tax-payable notification and statutory rules. |
| Mutual fund trusts and corporations other than Canadian-controlled private corporations | Generally four years | Measured using the relevant original assessment and statutory rules. |
The periods are not absolute. The Income Tax Act and CRA guidance recognize extensions and exceptions, including certain misrepresentations attributable to neglect, carelessness, or wilful default; fraud; a valid waiver; and specific items that have their own extended period. A return can therefore be reassessed after the usual three- or four-year window in circumstances covered by those provisions.
Do not calculate the end date from memory. Confirm the date of the original assessment or relevant notification, your taxpayer category, whether a waiver exists, and whether the issue has a special rule. Keep copies of the notice and any waiver or correspondence.
How long you generally have to object to a CRA notice
An objection is the formal process for disputing an assessment or reassessment. Section 165 of the Income Tax Act sets the statutory framework; see the Department of Justice text of section 165 and CRA’s objection guide.
| Taxpayer | General timing described by CRA | Important limits |
|---|---|---|
| Individual other than a trust or graduated rate estate | The later of one year after the return’s filing deadline or 90 days after the date CRA sent the notice. | Special assessment types, filing situations, and statutory rules can change the result. Check the notice and current CRA guidance. |
| Corporation | Generally 90 days from the date CRA sent the notice. | Large corporations and particular issues have additional rules and requirements. |
| Trust, graduated rate estate, or another taxpayer | Not safely determined from the individual summary above. | Use the rule for that taxpayer category and notice; obtain advice where necessary. |
The deadline starts from the relevant dates specified by law, not from the day you happen to open the envelope or log in. Record the notice date, the tax year, the return’s filing deadline, and the date you filed any objection. If you are close to the deadline, file according to CRA’s instructions first and provide additional explanation or documents as permitted.
Step-by-step: responding to a reassessment
1. Identify the document and deadline
Confirm whether you received a notice of assessment, notice of reassessment, or another determination. Note the tax year, notice date, taxpayer name and type, amount changed, and the deadline calculated under the applicable rule. Save the original document and the electronic version if available.
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Compare the reassessment with your filed return and the earlier notice. List each changed line, credit, deduction, income amount, interest calculation, and penalty. Gather the return, schedules, slips, receipts, work papers, correspondence, and any document CRA requested.
3. Ask CRA for an explanation if needed
CRA encourages taxpayers who do not understand a notice to contact it for an explanation. Ask what item was changed, why it was changed, and what information CRA considered. Keep a record of the date, the representative’s name or identifier if provided, and any follow-up requested. Contacting CRA is useful for clarification but is not a substitute for filing an objection.
4. Decide whether an adjustment request or an objection is appropriate
If you are asking CRA to correct your own return and no disputed assessment deadline is at risk, a taxpayer-requested adjustment may be suitable. If CRA has issued a notice and you disagree with it, use the formal objection process. Do not assume that a pending adjustment request preserves the objection deadline.
5. Prepare a focused objection
State the tax year and notice date, identify every amount or issue disputed, explain the facts and legal or factual basis for your position, and attach documents that support it. Separate facts from assumptions. If only one item is wrong, identify that item rather than making an unsupported challenge to the entire return.
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6. Submit it using the current CRA instructions
Follow the submission method and address in the notice and CRA’s current objection guide. Keep a complete copy of what you sent, proof of delivery or electronic confirmation, and a calendar reminder to monitor CRA’s response. If documents are too large or unavailable, explain what is missing and when it can be supplied.
A request to change your return is not an objection
A taxpayer-requested adjustment is a request to change a previously filed return. CRA’s publication Taxpayer Requested Adjustments: Reassessment of a Return of Income states that CRA may or may not issue a reassessment in response and that the request itself is not a notice of objection.
This distinction matters when a notice has already been issued. An adjustment request may be accepted, denied, or partially processed, but it does not automatically start the formal dispute process or extend the objection deadline. If CRA later sends a reassessment and you disagree, calculate the objection deadline for that notice and file the objection even if your adjustment request remains outstanding.
| Situation | Appropriate action | What it does not do |
|---|---|---|
| You found a mistake in your filed return and want CRA to change it. | Submit a taxpayer-requested adjustment under CRA’s process. | It does not constitute a notice of objection. |
| CRA issued a reassessment and you disagree with the result. | File a formal objection within the applicable deadline. | Calling CRA or requesting an adjustment does not replace the objection. |
What happens after an objection
CRA’s Appeals Branch reviews an objection separately from the original assessment process. CRA describes its mandate this way: Our skilled workforce will conduct a fair, complete, and impartial review, and actively engage in dialogue with taxpayers.
That is the agency’s description of its mandate, not a promise about the result of any particular objection.
CRA may allow the objection, vary the assessment, or confirm it. Keep responding to information requests and update CRA if your address or representative changes. If the decision does not resolve the dispute, read the decision date and the appeal instructions immediately.
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Appealing to the Tax Court of Canada
According to CRA’s dispute guide, a taxpayer generally has 90 days after CRA sends its objection decision for the Tax Court of Canada to receive a notice of appeal. The guide also describes access to the Tax Court when CRA has not issued a decision within 90 days after the objection was filed. These are separate rules from the original objection deadline.
Tax Court procedure has filing requirements, service rules, and jurisdictional limits. A high-value, technically complex, or time-sensitive case may justify advice from a Canadian tax lawyer or qualified tax-dispute representative. Do not wait for informal discussions with CRA to expire before checking the court deadline.
Collection and interest while you dispute a reassessment
Filing an objection does not erase the amount on the notice. CRA normally postpones collection action on disputed amounts during specified objection and appeal periods, subject to statutory exceptions. The rules differ for some large corporations and certain categories of disputed amounts.
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Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteInterest generally continues to accrue on amounts owing while the dispute is underway. A later reduction may reduce the principal and related interest, but you should not assume that interest stops when you object. Check the notice and CRA’s current collection rules, and consider payment or other arrangements where cash flow and potential interest make that important.
Worked examples of the separate clocks
Example: an individual’s objection window
Assume an individual’s return had an April 30 filing deadline and CRA sent a reassessment dated August 15, 2025. Ninety days after the notice would fall in November 2025; one year after the filing deadline would be April 30, 2026. Under the general individual rule, the later date would ordinarily govern. This is an illustration only: the notice type, taxpayer status, filing history, and statutory exceptions must be checked for the real case.
Example: a corporation
Assume a corporation receives a reassessment dated March 10. The general corporate period is 90 days from the notice date, subject to rules for the corporation’s status and the issue. The corporation should not use the individual “later of” calculation without confirming that it applies.
Example: CRA’s reassessment period versus your objection period
CRA may generally have three years, or four years for certain taxpayers, to reassess. If CRA reassesses within that period, your objection deadline is calculated from the reassessment notice and the rule for your taxpayer category. The end of CRA’s reassessment period does not give you extra time to object to a notice already issued.
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Common mistakes and how to avoid them
- Assuming reassessment means more tax: Check whether the notice increased, reduced, or confirmed the amounts.
- Treating three or four years as an absolute limit: Review possible extensions, waivers, fraud or misrepresentation rules, and issue-specific provisions.
- Using the reassessment period as your objection deadline: They are different clocks with different starting points.
- Waiting for a phone explanation: Ask questions, but preserve the formal filing deadline independently.
- Calling an adjustment request an objection: A taxpayer-requested adjustment does not constitute a notice of objection.
- Assuming an objection stops interest: Collection may be postponed in defined circumstances, while interest generally continues.
- Relying on a generalized date calculator: Verify the notice date, tax year, taxpayer category, filing deadline, and any special rule.
- Sending unsupported arguments: Tie each disputed amount to the return, records, facts, and applicable law, and keep copies of every submission.
Questions to answer before you act
Use this checklist when a CRA notice arrives:
- What is the tax year and the exact notice type?
- What date does CRA show as the notice date?
- Which lines, credits, deductions, income amounts, interest, or penalties changed?
- Is the taxpayer an individual, corporation, trust, graduated rate estate, or another category?
- Was a taxpayer-requested adjustment already submitted, and when?
- What is the objection deadline under the rule for this notice?
- What documents prove the facts?
- Will collection be postponed, and what interest will continue?
- If CRA confirms the reassessment, when does the 90-day Tax Court period begin?
Canadian federal income-tax deadlines and rights are notice-specific. Start with the document in front of you, verify the current CRA guidance and legislation, and obtain professional advice when the amount, facts, or deadline makes an error costly.
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