Guide · Tax numbers

How to validate a GST/HST/QST registration number

Check a supplier's registration with the CRA GST/HST Registry and Revenu Québec before you claim input tax credits or refunds

Published: 2026-09-30·5 min read

You can only claim input tax credits (ITC) for GST/HST that a registered supplier actually charged you, and in Quebec the same logic applies to QST refunds. Checking a supplier's registration number takes a minute and is the simplest way to protect those claims. This guide explains what a registration number looks like, which official tools validate it, and what to do when a number does not check out. Sources consulted on 2026-09-30: canada.ca (CRA) and Revenu Québec.

What a GST/HST or QST number looks like

A GST/HST account number is a 9-digit business number followed by the program identifier RT and a 4-digit reference, for example 123456789 RT 0001. The QST registration number is issued by Revenu Québec and ends with the letters TQ. When a Quebec supplier's QST number has only nine digits, no TQ and is identical to its GST/HST number, Revenu Québec treats it as a special case (a selected listed financial institution) and points you to the CRA to verify it.

Validate a GST/HST number with the CRA

The CRA GST/HST Registry is the official tool. You enter only the first nine digits of the account number (no letters), the supplier's business name as shown on an invoice or sign, and the date of the transaction (the date on the invoice, receipt or contract). It confirms whether that account was registered on that date. The CRA advises printing the Search Details screen as your record. The registry is as current as CRA records, and commercial reproduction of its results is prohibited.

Validate a QST number with Revenu Québec

Revenu Québec offers an online service to check the validity of a QST registration number. It returns the registration status, a status description, the effective date and the business name. It is open to businesses, self-employed workers, corporations and suppliers outside Quebec. Revenu Québec also publishes an API so you can validate supplier QST numbers automatically. The Revenu Québec service checks only QST numbers: for the GST/HST number of the same supplier, use the CRA registry.

Why it matters: ITC and ITR claims

The CRA states that the registry helps you claim input tax credits only for GST/HST charged by suppliers who are registered. If a supplier was not registered when it invoiced you, the tax it showed was not GST/HST it was entitled to collect, and a claim built on that invoice can be denied on review. Keeping the validation printout with the invoice gives you evidence if you are ever audited. The same care applies to QST amounts you claim as an input tax refund.

Invalid, revoked or not found — what to do

First re-check for typing errors, the exact business name and the transaction date, since the registry answers for a specific date. If the number was not registered on that date, ask the supplier for its correct number in writing. A new registrant may simply not be in the records yet. If the supplier cannot prove registration, do not claim the tax; call the CRA business enquiries line at 1-800-959-5525 for questions about a particular registration.

Do you need a number yourself?

You must register once your revenue from worldwide taxable supplies exceeds $30,000 in a single calendar quarter or over the last four consecutive calendar quarters. Below that you are a small supplier and registration is voluntary. Until you register you cannot charge GST/HST or claim ITCs, and your customers cannot validate a number you do not have. Confirm current thresholds and Quebec QST rules on canada.ca and revenuquebec.ca.