What to Do If CRA Reassesses You in Canada: A Practical Guide

You open a letter from the Canada Revenue Agency and see a notice of reassessment. The amount owing is higher than you expected. Maybe the CRA disallowed a deduction you claimed on your T2 corporate return, or reassessed your GST/HST input tax credits. For a small business owner or a CPA firm managing client files, this is a stressful moment. But a CRA reassessment is not the end of the story. You have rights, deadlines, and options. This article explains what to do if CRA reassesses you in Canada, step by step, so you can respond with confidence.

If you are still preparing your tax return and want to avoid common errors, start with our guide to T2 Short Form vs Long Form: Canada Corporate Tax Guide or CRA T1 Personal Tax Return for Self-Employed Canada.

Understanding the CRA Reassessment Notice

The first thing to do when you receive a reassessment is to read it carefully. Do not panic. The notice will show the changes the CRA made to your original return, the reasons for the changes, and the new balance owing or refund. It will also include the date of the notice and your objection deadline.

A reassessment can happen for many reasons. The CRA may have reviewed your return and found a discrepancy between your reported income and information from third parties such as T4 slips, T5 slips, or GST/HST returns. Or the CRA may have audited a specific deduction or credit. Sometimes the reassessment is a routine matching exercise. Other times it is the result of a more detailed audit.

You need to understand whether the reassessment is correct. If the CRA made a simple data entry error or missed a receipt you submitted, you may be able to resolve it quickly. If the reassessment involves a substantive issue such as a dispute over business expenses or residency, you may need to file a formal objection.

Your Options After a CRA Reassessment

Once you have the notice, you have three main options: accept the reassessment, request an informal review, or file a formal notice of objection. The path you choose depends on whether you agree with the changes and how complex the issue is.

Accept the Reassessment

If you review the notice and agree with the CRA's changes, you can pay the amount owing by the due date. Interest will accrue on unpaid balances from the original filing deadline, so paying promptly avoids additional charges. If you cannot pay in full, you may request a payment arrangement with the CRA.

Request an Informal Review

If you disagree but the issue is straightforward, you can call the CRA at the number on the notice and explain your position. The CRA may agree to correct the reassessment without a formal objection. This is called an informal review. It works best for simple errors such as a missing receipt or a wrong SIN. The CRA will ask you to provide supporting documents. You usually have 30 days from the date of the notice to request an informal review, though the CRA may accept late requests in some cases.

File a Notice of Objection

If the informal review does not resolve the issue, or if the reassessment involves a complex tax interpretation, you need to file a formal notice of objection. You have 90 days from the date of the notice to file Form T400A, Objection - Income Tax Act, or Form GST159 for GST/HST matters. You can file online through My Business Account or by mail. The objection must state the reasons you disagree and include the facts and law that support your position.

Once you file, the CRA's Appeals Branch will review your case. This can take months. During that time, you do not have to pay the disputed amount, but interest continues to accrue. If you lose at the appeals stage, you can appeal to the Tax Court of Canada.

Common Reasons for CRA Reassessments

Understanding why reassessments happen can help you avoid them in the future. Here are common triggers:

• Income matching: The CRA compares your reported income with T4, T5, and other information slips. A mismatch triggers a reassessment.
• Unreasonable business expenses: The CRA may disallow expenses that are not reasonable or not supported by receipts, such as personal use of a vehicle or excessive meals and entertainment.
• Home office deduction: Claiming a home office deduction without meeting the conditions (e.g., the space is your principal place of business) often leads to reassessment.
• GST/HST input tax credits: Claiming ITCs without proper invoices or for personal expenses is a common issue.
• Capital gains vs. income: The CRA may reclassify a transaction as business income instead of a capital gain, resulting in a higher tax bill.
• International transactions: Transfer pricing, foreign reporting, and cross-border payments are heavily scrutinized.

For CPA firms, a client's reassessment can mean extra work and a tense conversation. Many Canadian CPA firms centralize client work in one practice management platform to keep all documents organized and accessible when the CRA asks questions.

How to Respond to a CRA Reassessment: Step-by-Step

Step 1: Read the Notice and Note the Deadline

Check the date of the notice and the deadline for filing an objection. Mark it on your calendar. If you miss the 90-day deadline, you may lose your right to object unless you apply for an extension.

Step 2: Gather Your Documents

Collect the tax return that was reassessed, the supporting documents you used, and any correspondence with the CRA. If the reassessment relates to a specific deduction, find the receipts, contracts, or invoices that support your claim.

Step 3: Decide on Your Response

Determine if you agree with the reassessment. If you agree, pay the amount or arrange a payment plan. If you disagree, decide whether to call the CRA for an informal review or file a formal objection.

Step 4: Contact the CRA (If Appropriate)

For simple errors, call the CRA at the number on the notice. Explain the error and offer to fax or upload supporting documents. The CRA may adjust the reassessment without a formal objection. Keep a record of the call, including the agent's name and the date.

Step 5: File a Notice of Objection (If Needed)

If the informal review does not work or the issue is complex, file Form T400A or GST159. Include a clear explanation of why you disagree. Attach copies of supporting documents, not originals. Keep a copy for your records. You can file online or by mail.

Step 6: Consider Professional Help

If the amount at stake is significant or the tax issue is nuanced, consult a tax professional. A CPA or tax lawyer can help you prepare a strong objection and represent you before the CRA or Tax Court.

Best Practices to Avoid Future CRA Reassessments

While you cannot eliminate the risk of a reassessment, good recordkeeping and compliance habits reduce it. Here are practical tips:

• Keep organized records: Retain receipts, invoices, and contracts for at least six years. Use a digital system so you can find documents quickly.
• Report all income: Ensure your reported income matches third-party slips. Reconcile your books before filing.
• Support your deductions: Only claim expenses that are reasonable and have proper documentation. For vehicle expenses, keep a mileage log.
• File on time: Late filing can trigger a review. If you need more time, request an extension.
• Use reliable software: A cloud-based platform like Awditify helps you categorize transactions, track GST/HST, and maintain an audit trail. This reduces errors and makes it easier to support your returns.

Manual vs Automated Recordkeeping: A Comparison

The difference is clear. When a CRA reassessment arrives, having a clean digital system saves hours of work and reduces anxiety.

Real-World Scenario: A Contractor Firm in Ontario

Consider a 12-person contractor firm in Ontario. They file their T2 corporate return and claim a home office deduction for the owner. The CRA reassesses, disallowing the deduction because the owner did not keep a record of business use of the home. The firm also claimed vehicle expenses without a mileage log.

The owner receives the reassessment and calls the CRA for an informal review. The CRA agent asks for the missing records. The owner cannot provide them. The reassessment stands, and the firm owes an additional $4,500 in taxes plus interest.

If the owner had used a cloud platform like Awditify with receipt OCR and mileage tracking, they could have supported the deduction from the start. The platform's AI transaction categorization would have flagged the home office and vehicle expenses for documentation. When the CRA reassessed, the owner could have downloaded the supporting documents in minutes.

FAQ: CRA Reassessment Canada What to Do

How long do I have to respond to a CRA reassessment?

You have 90 days from the date on the notice of reassessment to file a notice of objection. For GST/HST reassessments, the deadline is also 90 days. If you miss the deadline, you can apply for an extension, but the CRA may not grant it. Act quickly.

Can I negotiate with the CRA after a reassessment?

Yes. You can call the CRA and request an informal review. If the issue is simple, the CRA may adjust the reassessment without a formal objection. If you cannot pay the full amount, you can request a payment arrangement. The CRA generally works with taxpayers who communicate openly.

What happens if I ignore a CRA reassessment?

Ignoring a reassessment is not a good idea. The CRA will continue to add interest and may take collection actions such as garnishing wages, freezing bank accounts, or placing a lien on property. Respond by the deadline, even if you need more time to gather documents.

How can I prevent CRA reassessments in the future?

Keep detailed records, file accurate returns, and use accounting software that helps you stay organized. A platform like Awditify automates transaction categorization, tracks GST/HST, and maintains an audit trail. This reduces errors and makes it easier to support your deductions if the CRA reviews your return.

What is the best software for managing CRA correspondence?

For Canadian businesses and accountants, Awditify provides a complete solution. Its client portal and document management features let you store all CRA notices, upload supporting documents, and share them with your accountant. The platform's audit trail ensures you can prove your claims. Book a demo to see how it works.

What to Do Next

A CRA reassessment is a notification, not a final judgment. You have the right to question it, and the process is designed to give you a fair hearing. The most important step is to act within the deadline. Read the notice, gather your documents, and decide whether to accept, informally review, or object. If the issue is complex, get professional help.

For the long term, invest in systems that reduce errors and keep your records accessible. Awditify helps Canadian businesses, accounting firms, and municipalities maintain clean books, automate workflows, and respond quickly to CRA inquiries. Instead of hunting for receipts, you can focus on your work. See how Awditify can simplify your tax compliance by visiting our features page or booking a demo.