How to Verify a Supplier’s GST/QST Registration Number

Introduction
Verifying a supplier’s GST (Goods and Services Tax) and QST (Quebec Sales Tax) registration numbers is one of the most critical steps in protecting your business from denied tax credits, reassessments, and costly penalties. Both the Canada Revenue Agency (CRA) and Revenu Québec (ARQ) require that all Input Tax Credits (ITCs) and Input Tax Refunds (ITRs) claimed on your tax return be supported by invoices that show valid supplier tax registration numbers.

Unfortunately, many small businesses in Quebec lose thousands of dollars each year because they fail to confirm that their suppliers are properly registered. Auditors frequently deny ITCs and ITRs when the supplier’s registration is invalid, expired, or incomplete—even if the expense was legitimate.

At Mackisen CPA Montreal, we’ve helped businesses verify supplier registration numbers and strengthen their audit defense systems for over 35 years. This guide explains how to confirm supplier numbers under the law, how to spot red flags, and how Mackisen can protect your tax credits before the CRA or Revenu Québec ever questions them.

Legal and Regulatory Framework
The requirement to verify supplier registration is grounded in both federal and provincial law:

• Excise Tax Act (Canada) s.169(4) — Taxpayers can claim Input Tax Credits (ITCs) only when invoices include the supplier’s valid GST registration number.

• Taxation Act (Quebec) s.250 and s.257 — Similar rules apply to QST Input Tax Refunds (ITRs). Invoices must show the supplier’s valid QST registration number.

• Tax Administration Act (Quebec) s.34 — Requires registrants to maintain proof of all claimed credits and refunds for six years.

If your supplier’s GST or QST number is invalid or missing, CRA or Revenu Québec may deny your ITC/ITR claim even if the purchase was business-related and taxes were paid.

Step-by-Step: How to Verify a Supplier’s GST/QST Number

1. Obtain the Supplier’s Full Invoice
   Make sure the invoice includes:

   • Supplier’s business name, address, and contact information.

   • Supplier’s GST number (RT code) and QST number (TQ code).

   • Taxable amount, GST (5%), and QST (9.975%) shown separately.

   • Date and invoice number.

2. Verify the GST Number Online (CRA)

   • Go to the CRA GST/HST Registry: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/verify-gst-hst-account.html

   • Enter the GST number from the invoice and the date of the transaction.

   • Confirm that the business name and address match your supplier’s invoice.

   • Print or save the confirmation for your records.

3. Verify the QST Number Online (Revenu Québec)

   • Visit Revenu Québec’s QST Registration Verification tool: https://www.revenuquebec.ca/en/online-services/businesses/verify-a-qst-registration-number/

   • Input the supplier’s QST number (format: TQ1234567890).

   • Validate that the name, address, and status are correct and that the registration is active.

   • Keep a copy of the result (screenshot or PDF).

4. Maintain Verification Records

   • Create a “Supplier Verification Log” in your accounting system or a separate folder.

   • Record the verification date, who performed it, and results (active/inactive).

   • Retain a PDF of both CRA and Revenu Québec verification pages with the invoice.

5. Reverify Annually or When Red Flags Appear

   • If a supplier changes names, addresses, or banking details, recheck their registration.

   • For high-value purchases or subcontractors, confirm validity before every payment.

Jurisprudence and Legal Insights
Canadian and Quebec courts have repeatedly ruled that the burden of proof lies with the taxpayer to confirm supplier legitimacy:

• Hickman Motors Ltd. v. Canada (SCC 1997) — CRA assessments are presumed correct; taxpayers must provide evidence to disprove them.

• Canderel Ltd. v. Canada (SCC 1998) — Commercial accuracy and verification are essential for tax compliance.

• Vancouver Art Metal Works Ltd. v. Canada (FCA 2015) — ITCs were denied because invoices lacked valid GST registration numbers, even though services were provided.

In practice, this means that even if your supplier collects and remits taxes, you can lose your refund if you didn’t verify their registration.

Documentation: What to Keep for CRA and Revenu Québec
Keep the following documentation to support your ITCs and ITRs:

• Supplier invoices showing both registration numbers.

• CRA and ARQ verification screenshots or printouts.

• Bank proof of payment (cheque, EFT, credit card).

• Supplier contracts and business correspondence.

• Yearly supplier verification log maintained by your accountant.

At Mackisen CPA Montreal, our compliance team organizes this data into your Audit-Ready Supplier Binder, ensuring every tax credit claimed is backed by verifiable proof.

How CRA and Revenu Québec Audit Supplier Verification
During audits, both agencies cross-check your supplier invoices against their registration databases. They examine:

• Whether supplier GST/QST numbers were valid at the time of the transaction.

• Whether the supplier was an active registrant.

• If your ITCs/ITRs were claimed based on invoices missing required details.

If discrepancies exist, CRA or Revenu Québec may deny credits, reassess past returns, and apply penalties under Tax Administration Act s.59 or Excise Tax Act s.280(1).

Winning With CRA and Revenu Québec
At Mackisen CPA Montreal, our strategy for defending denied credits and preventing reassessments includes:

1. Supplier Verification Audit – We review every supplier invoice for compliance.

2. Evidence Reconstruction – If records are missing, we retrieve verification proofs directly from CRA and ARQ databases.

3. Legal Representation – Our tax lawyers communicate with CRA/ARQ auditors, submitting verified documentation and explanations.

4. Penalty Relief – We file applications under Tax Administration Act s.94.1 for penalty reduction where errors occurred in good faith.

5. System Implementation – We create automated verification workflows in your accounting software for all new suppliers.

Mackisen Service Hub: Supplier Compliance and Audit Defense
Our Mackisen Service Hub ensures supplier compliance at every level. We provide:

• Real-time CRA and ARQ number verification.

• Supplier compliance monitoring and audit tracking.

• Electronic proof management for ITC/ITR claims.

• Pre-audit verification and staff training for accounts payable teams.

Our CPA auditors, tax lawyers, and compliance specialists—all trained at McGill, Université de Montréal, and Concordia University—work together to ensure your GST/QST credits withstand any audit.

Real Client Example
A Montreal construction firm had $84,000 in denied Input Tax Refunds after Revenu Québec found that two subcontractors’ QST numbers were inactive. Mackisen CPA retrieved proof that both suppliers were active at the time of invoicing, provided CRA verification logs, and filed a formal objection under Tax Administration Act s.93.1. Within 10 weeks, the reassessment was reversed, and the client recovered the full refund.

Why Mackisen
With over 35 years of combined CPA and legal experience, Mackisen CPA Montreal is the trusted partner for supplier verification and tax compliance. We ensure every supplier you pay and every tax credit you claim is fully verified, documented, and audit-ready.

When you work with Mackisen, you gain confidence that your books are accurate, your refunds are protected, and your business stands on unshakable compliance.