CRA Reassessment: Your Timeline, Rights, and How to Respond

A reassessment changes the assessment of tax you already received. CRA has the authority to issue reassessments under the Income Tax Act, but that authority is bounded by specific time limits, defined exceptions, and a structured process. Understanding the rules helps Calgary taxpayers know whether a reassessment is properly issued, what their rights are at each stage, and when to push back. This guide covers the normal reassessment period, the exceptions that extend it, your rights as a taxpayer, and the practical response strategy.

The Normal Reassessment Period

For individuals filing T1 returns and Canadian-controlled private corporations (CCPCs) filing T2 returns, the normal reassessment period is three years from the date of the original Notice of Assessment. After three years, CRA generally cannot reopen the return unless an exception applies. For non-CCPCs (large corporations, mutual fund corporations) the period is four years. For trusts, three years. For GST/HST returns, four years. The clock starts on the date CRA issues the original assessment, not the date you filed.

When the Three-Year Limit Is Extended

Several exceptions extend the reassessment period beyond the normal three years. The most common is misrepresentation due to carelessness, neglect, or wilful default. CRA can reassess any year, no matter how old, if they can demonstrate that the misrepresentation meets this standard. The bar is lower than fraud but higher than honest mistake. Other extensions include waivers signed by the taxpayer (often during an audit, extending the reassessment period for one year), transactions involving non-arm's length parties, transactions involving foreign affiliates (additional three years), and certain prescribed transactions and aggressive tax planning arrangements. Each extension has specific requirements CRA must meet to invoke it.

Common Triggers for Reassessment

Most reassessments fall into a handful of categories. Missing or unreported information slips (T4, T5, T3, T5008) detected when CRA matches your return to slip data submitted by third parties. Adjustments after a CRA review of specific deductions (employment expenses, medical, charitable donations). Adjustments after a desk audit or field audit of one or more years. Reassessments after the courts decide a tax case that applies to similar taxpayers. Reassessments after CRA receives information from a foreign tax authority under treaty information exchange. Reassessments after a Voluntary Disclosure Program application is accepted. Reassessments after the Auditor General or Internal Audit identifies a systemic issue.

Your Rights at Reassessment

Canadian taxpayers have specific rights when CRA reassesses a return. The right to receive clear information about the proposed reassessment and the reasons for it. The right to be represented by a CPA or other professional throughout the process. The right to provide additional information before CRA finalizes the reassessment. The right to a fair and impartial review, including by the Appeals Division if you object. The right to file a Notice of Objection within 90 days. The right to appeal to the Tax Court of Canada if the Appeals Division does not resolve the matter in your favour. The right to professional treatment by every CRA employee you deal with. These rights are summarized in the Taxpayer Bill of Rights and are enforceable through the Office of the Taxpayers' Ombudsperson.

Proposed Adjustments vs. Final Reassessments

Most reassessments follow a proposed adjustment letter. CRA writes to you outlining the proposed changes and explaining their reasoning, then gives you 30 days (sometimes longer for complex audits) to respond. The proposal stage is your best opportunity to influence the outcome. Provide additional documentation, correct factual errors, cite authority that contradicts CRA's position, or accept the proposal where it is correct. If you do not respond, CRA finalizes the proposed adjustments and issues a Notice of Reassessment. The objection process then becomes your only remaining route to dispute the assessment. A CPA can often resolve issues at the proposed adjustment stage that would otherwise become full objections.

Reading a Notice of Reassessment

A Notice of Reassessment includes the tax year being reassessed, the original assessed amounts, the reassessed amounts, the difference, interest calculated on the difference, any penalties applied, the date of the reassessment (which starts your 90-day objection clock), and contact information for the assigned officer. Read it carefully. Verify the math. Identify each item that changed. Confirm the dates. Sometimes the reassessment includes obvious errors (math, dates, double-counted items) that can be corrected with a phone call. Other times the issue is substantive and requires a formal objection.

Interest and Penalty on a Reassessment

Interest is charged on the additional tax from the original payment due date for that year, not from the date of the reassessment. This means a 2022 tax year reassessment issued in 2026 carries roughly four years of compounded interest at the prescribed rate (currently in the 9-10% range annually for the late payment rate). Penalties may also apply: late filing penalty if the return was late, gross-negligence penalty if CRA alleges that level of conduct (50% of the unreported tax), repeated failure to report income penalty (10% to 20% of the unreported amount), and gross-negligence penalty for false statements. Interest and penalties often exceed the tax at stake on older reassessments. Resolution speed matters financially.

What to Do When a Reassessment Arrives

First, do not panic. Most reassessments can be resolved through proper channels. Second, note the date on the reassessment and mark 90 days forward on your calendar (the objection deadline). Third, read the reassessment carefully and identify every change. Fourth, gather the documentation you have for the years involved. Fifth, contact a CPA. Even a fifteen-minute call can determine whether the reassessment is correctable informally, requires a formal objection, or warrants accepting and paying. Avoid calling CRA directly until you have professional advice. Anything you say is recorded and may be used against your position later.

If You Agree With the Reassessment

If you review the reassessment and agree it is correct (you genuinely missed a slip, claimed a deduction you should not have, or made a calculation error), pay the additional tax and interest promptly to stop further interest accrual. Penalties may be subject to relief under the Taxpayer Relief Provisions if extraordinary circumstances led to the error. A CPA can prepare a relief request that often results in penalty reduction or elimination. Even when you agree with the tax owing, professional help with the interest and penalty can save thousands.

Strategic Considerations for Older Years

If a reassessment is issued for a year that is beyond the normal three-year period, CRA must justify the extension. Frequently CRA invokes 'carelessness or neglect' without a strong factual basis. Pushing back on this characterization, with evidence that the original filing was reasonable and made in good faith, can defeat the reassessment entirely on procedural grounds. This is a technical argument that requires a CPA's involvement. Self-represented taxpayers rarely raise it. The opportunity costs of letting an out-of-period reassessment stand are significant.

When to Get Help

Any reassessment over $5,000 in additional tax warrants a CPA review. Any reassessment involving multiple years, an audit context, or complex issues (corporate, foreign, rental, business income) warrants professional handling from the start. At Finsight Accounting we review reassessments at no charge to determine whether action is warranted. Many of the Calgary taxpayers who contact us would have accepted reassessments they did not need to pay, simply because the dispute path was not explained to them. Knowing your rights is the first step to exercising them.