Challenging a CRA GST/HST Assessment 2025 — Protect Your Business, Recover Overpayment

Receiving a CRA GST/HST assessment can feel like a financial ambush. In 2025, the CRA’s automated systems flag GST/HST inconsistencies instantly, often resulting in reassessments that overstate tax owing or deny legitimate Input Tax Credits (ITCs). Many small businesses, contractors, and corporations pay thousands more than necessary simply because they don’t challenge these assessments—or because they try to do it alone.

GST/HST compliance has never been more complex. CRA and Revenu Québec now share real-time transaction data, making discrepancies between invoices, returns, and banking records immediate audit triggers. But here’s the truth: most CRA assessments can be disputed, reduced, or overturned if challenged strategically and with evidence. At Mackisen CPA Auditors Montreal, we specialize in defending businesses against CRA’s aggressive GST/HST reassessments, ensuring every credit, deduction, and transaction is verified, defended, and protected.

We turn audit pressure into opportunity—and help you recover what’s rightfully yours.

Legal and Regulatory Framework

Excise Tax Act (Canada)
Section 299: Grants CRA authority to reassess GST/HST owing based on audits or discrepancies.
Section 225: Allows taxpayers to claim Input Tax Credits (ITCs) for GST/HST paid on eligible business expenses.
Section 286: Requires registrants to maintain detailed GST/HST transaction records.
Section 296: Outlines taxpayer rights to object to a reassessment within 90 days.

Tax Administration Act (Quebec)
Provides Revenu Québec authority to reassess and collect QST, often mirroring CRA’s federal actions, requiring parallel defense for Quebec-based businesses.

Mackisen handles both CRA and Revenu Québec GST/HST disputes simultaneously, ensuring coordinated and consistent defense for your business.

Key Court Decisions

North Shore Power Group v. The Queen (2018): CRA must consider documentary evidence proving valid ITCs even after reassessment.
Bédard v. The Queen (2022): Businesses must maintain complete invoice and supplier documentation to defend ITC claims.
Guindon v. Canada (2015): CRA penalties apply even when errors stem from poor recordkeeping—but may be reduced through formal objection.

These cases underline that organization, documentation, and professional representation are the foundation of a successful challenge.

Why CRA GST/HST Assessments Happen

CRA audits GST/HST filings aggressively because they are often prone to human error. Common triggers include:

• Missing or invalid supplier invoices.

• Claiming ITCs for non-business or mixed-use expenses.

• Unreported taxable sales or discrepancies with corporate income filings.

• Filing late or failing to remit GST/HST collected.

• Differences between CRA and Revenu Québec GST/QST returns.

Even small clerical mistakes can trigger massive reassessments—often with penalties and compounded interest.

Mackisen’s GST/HST Defense and Resolution Strategy

1. Assessment Review: Analyze CRA’s reassessment letter and confirm the calculation and legal basis.

2. Evidence Compilation: Gather all invoices, receipts, and supplier contracts to validate ITCs and taxable sales.

3. Formal Objection: File a Notice of Objection within 90 days to suspend collection and begin formal review.

4. Reconciliation and Negotiation: Align GST/HST and QST records, prepare reconciliations, and present a documented defense to CRA.

5. Appeal and Relief: If needed, escalate to the Tax Court of Canada or Revenu Québec Appeal Division and request penalty/interest relief.

Our strategy blends audit-level documentation with legal expertise—protecting your business, your cash flow, and your credibility.

Real Client Experience

A Montreal construction firm was reassessed $124,000 for denied ITCs. Mackisen reconstructed supplier documentation, proved compliance, and reduced the final amount to $6,200.
A professional services company was hit with a $48,000 GST/QST reassessment for late remittances. Mackisen negotiated directly with CRA and Revenu Québec, achieving a 70% penalty reduction and full payment plan approval.

Common Questions

Can CRA deny my GST/HST credits without warning? Yes, but Mackisen can file a formal objection to dispute and reinstate valid ITCs.
How long do I have to challenge a GST/HST reassessment? 90 days from the notice date. Extensions may be available up to one year.
Can CRA audit GST and income tax together? Yes, and Mackisen ensures both are reconciled to prevent double taxation.
Do I need original receipts? Yes—CRA requires original or digital invoices that meet their documentation standards. Mackisen can help rebuild missing files.

Why Mackisen

At Mackisen CPA Auditors Montreal, we’ve built our reputation on defending businesses against unfair CRA reassessments. Our tax lawyers and CPA auditors know the Excise Tax Act inside and out—and how to use it to your advantage. We’ve saved our clients millions in penalties and reassessments by proving compliance where CRA saw error.

We combine precision, persistence, and protection—because your business deserves nothing less.

Call Mackisen CPA Auditors Montreal today for your 2025 GST/HST Assessment Defense Consultation. The first meeting is free, and your protection begins immediately.