WHY DO I NEED A SEPARATE QST NUMBER IN QUEBEC?

Many new business owners are surprised to learn that, in Quebec, they receive two separate tax numbers when registering for sales tax: one for GST and one for QST. Even though both taxes are filed together using the FPZ-500-V return, Quebec still issues distinct registration numbers and maintains the QST as an independent tax system. This leads many entrepreneurs to ask: Why do I need a separate QST number if everything is filed at the same time? This guide explains the legal, administrative, and practical reasons behind Quebec’s dual-number system — and what it means for your business.

Understanding the separate numbers helps ensure compliant invoicing, proper filing, and smooth interaction with Revenue Québec.

LEGAL AND REGULATORY FRAMEWORK

The requirement for separate tax numbers comes from:

• the Excise Tax Act — which governs GST
• the Quebec Taxation Act — which governs QST

Although Quebec administers both GST and QST through Revenu Québec (under a federal–provincial agreement), the two taxes remain legally distinct systems with:

• separate legislation
• separate calculation rules
• separate audit processes
• separate input-tax mechanisms (ITCs vs. ITRs)
• separate rights of appeal

This separation is why your business receives two numbers.

KEY COURT DECISIONS

Courts have affirmed the distinct nature of GST and QST:

• QST cannot be treated as an extension of GST — it is legally independent
• GST/HST decisions do not automatically apply to QST cases
• taxpayers must comply with both sets of legislation
• appeals and disputes must be filed under the correct tax act
• errors in GST do not “cancel out” QST errors

Judges emphasize that GST and QST are parallel tax systems, even when administered together.

WHY QUEBEC USES SEPARATE QST NUMBERS

There are several important reasons.

1. QST is a provincial tax with its own legislation

Even though the systems look similar, the QST is not federally controlled. A separate number ensures compliance with Quebec’s laws.

2. Different calculation mechanisms

QST is calculated using a unique method, including tax-on-tax considerations historically. While the system has been harmonized somewhat, QST still behaves differently in specific scenarios.

3. Separate audits and verifications

Revenu Québec may audit your QST independently of your GST.
A separate number allows agents to track QST activity distinctly.

4. Separate input tax mechanisms

You claim:
• ITCs (Input Tax Credits) for GST
• ITRs (Input Tax Refunds) for QST

These mechanisms follow separate rules, deadlines, and eligibility criteria.

5. Non-resident suppliers follow different QST rules

Foreign and out-of-province suppliers may be required to register for a special QST number, even if they do not register for GST.

6. Legal appeals require separate identification

If a taxpayer disputes assessments, they must reference the correct tax number for:
• GST objections
• QST objections

7. Revenu Québec must track provincial revenue independently

The provincial government requires clear reporting of QST revenue separate from federal GST revenues.

WHAT YOUR SEPARATE QST NUMBER IS USED FOR

Your QST number is required for:

• all invoices issued to Quebec customers
• filing GST/QST returns
• responding to Revenu Québec audits
• registering employees or subcontractors
• applying for refunds
• opening a Mon Dossier business account
• tax clearance certificates

Even though both taxes appear on the same return, your QST number is central to your Quebec filing identity.

COMMON QUESTIONS ABOUT SEPARATE QST NUMBERS

“Why do GST and QST numbers look similar?”

Because both follow a standardized business number format — but they identify different accounts.

“Can I file GST without filing QST?”

No. In Quebec, GST and QST are filed together on the FPZ-500-V form.

“Can I charge QST without a QST number?”

No. You must have a valid registration number before charging QST.

“If I move out of Quebec, do I cancel my QST number?”

Only if you no longer make taxable supplies in Quebec.

“Do I need a QST number for online sales?”

Yes, if you sell taxable goods or services to Quebec customers and exceed registration thresholds.

MACKISEN STRATEGY

Mackisen CPA helps businesses understand Quebec’s dual-number system and ensures proper GST/QST registration. We set up your accounts in Revenu Québec and CRA systems, configure your invoicing, and train your staff on proper tax identification. Our team also ensures your accounting software is synced to use both numbers correctly.

For businesses operating in multiple provinces or internationally, we build tax matrices to ensure correct application of GST, HST, QST, and PST.

REAL CLIENT EXPERIENCE

A digital services company charged QST without a QST number. Mackisen corrected registration, fixed invoices, and avoided penalties.

A construction firm mixed GST and QST coding in their software. Mackisen reorganized tax settings and prevented under-collection.

A Shopify merchant used the wrong tax ID for Quebec clients. Mackisen updated templates and reconciled past filings.

COMMON QUESTIONS

What if I only sell to other provinces?
You do not need QST registration unless supplying taxable goods/services to Quebec.

Why does Revenu Québec handle GST?
Under a federal–provincial agreement, Quebec administers GST on behalf of the CRA.

Do I need both numbers on every invoice?
Yes. For Quebec customers, both GST and QST numbers must appear.

WHY MACKISEN

With more than 35 years of combined CPA experience, Mackisen CPA Montreal ensures businesses register, charge, and report Quebec sales tax correctly. We help you understand and manage both your GST and QST numbers with confidence.