A taxpayer who disagrees with an assessment or reassessment can formally dispute it. The first step is a Notice of Objection to the CRA; if the dispute is not resolved, the next step is an appeal to the Tax Court of Canada.
Filed online through My Account ("Register my formal dispute") or on Form T400A.
Deadline for individuals: the later of one year after the filing due date for the return, and 90 days after the date of the notice being objected to.
State the facts and reasons for the disagreement and include supporting documents.
An objection is reviewed by the CRA's Appeals Branch, which is separate from the auditors.
Collection of the disputed income tax is generally suspended while the objection is under review (interest continues to accrue).
If the deadline is missed, an extension can be requested within one year after it expired, with reasons.
The Appeals officer can confirm the assessment, vary it (fully or partly accept the objection), or vacate it. A notice of confirmation or reassessment is issued.
Must be filed within 90 days after the CRA's decision on the objection, or after 90 days if the CRA has not responded.
Informal procedure: available when the federal tax and penalties in issue are $25,000 or less per year (or the loss in issue is $50,000 or less). Simpler rules, no need for a lawyer, and decisions are not binding precedents.
General procedure: for larger amounts, with formal rules of evidence and procedure; representation by a lawyer is usual.
Further appeals go to the Federal Court of Appeal and, with leave, the Supreme Court of Canada.
Disputes about the Canada Child Benefit, Groceries and Essentials Benefit and similar benefits also follow the objection process.