How to Dispute a CRA or IRS Tax Assessment

Objection, Appeal, and Tax Court: Know the Ladder

Contesting a tax bill follows a defined ladder, and skipping a rung usually forfeits it. In Canada, you first file a Notice of Objection with the CRA Appeals Division within 90 days of the reassessment; if that is denied you may appeal to the Tax Court of Canada. In the United States, you can request an appeal with the independent IRS Office of Appeals, and a statutory 'notice of deficiency' gives you 90 days (150 if you are abroad) to petition the U.S. Tax Court without paying first. Each level has its own strict, generally non-extendable deadline printed on the notice.

The critical distinction most taxpayers miss is that deadlines run from the date of the notice, not from when you get around to reading it. Filing the objection or petition preserves every argument even if your evidence is still incomplete — you can supplement later. Waiting to assemble a perfect submission until after the deadline forfeits the right to dispute entirely and can leave you having to pay the assessment and then sue for a refund, a far harder road.

Factual Fixes vs Legal Arguments

Not every assessment needs a formal fight. A large share of reassessments come from a mismatch — a slip the agency has that you omitted, or a document you sent that was never matched to your file — rather than a genuine legal disagreement. For those, a phone call or a written request for reconsideration to the auditor can correct a clerical error faster and more cheaply than a formal objection. The rule is simply never to let an informal back-and-forth drift past your formal deadline: file to protect the date regardless of any informal progress.

Where you genuinely disagree on how the law applies, the dispute is won on a written legal argument, not on volume of paper. Set out the statutory provision, the interpretation you rely on, and any supporting case law or published agency guidance, and tie your evidence to each point. Disputes over penalties and interest are often separable from the underlying tax and may be resolved through relief provisions even when the tax stands, so identify which parts of the assessment you are actually contesting.

Do You Have to Pay While You Dispute?

Collection during a dispute differs by system and by tax type. In Canada, the CRA generally pauses collection of disputed income tax while an objection or Tax Court appeal is outstanding, though GST/HST and large-corporation rules can differ. In the United States, a timely Tax Court petition generally suspends collection of the disputed amount, but interest continues to accrue the entire time, so a long dispute over a small amount can cost more than it saves. Weigh the interest clock against the amount in play.

Throughout the process, keep everything in writing and respond promptly to the appeals officer's requests — an unanswered request can end a review against you. If your objection is denied, immediately calendar the next-level deadline so a Tax Court appeal does not lapse by default. This guide is educational only, is not tax or legal advice, and does not calculate your specific deadline; confirm your dates and strategy with a tax professional.

Related: Tax Law Wizards · Tax Appeal Readiness Check · Tax Audit Response Planner · Tax Penalty Relief Assessment · All Legal Wizards · AI Solutions for Law Firms