How to Self-Assess QST on Out-of-Province Purchases (Use Tax Obligations)

Introduction

Many Quebec businesses don’t realize that QST (Quebec Sales Tax) still applies even when they buy goods or services from outside Quebec. If a supplier doesn’t charge QST — for example, because they’re based in Ontario, Alberta, or another province — you may still have a legal duty to self-assess and remit the tax yourself.

This guide from Mackisen CPA Montreal explains how QST self-assessment works, when it applies, how to calculate and remit the correct amount, and how to stay compliant with Revenu Québec.

Legal and Regulatory Framework

Self-assessment obligations are governed by:

• Quebec Sales Tax Act (R.S.Q., c. T-0.1)

• Tax Administration Act (RLRQ, c. A-6.002)

Under these laws, businesses registered for QST must account for and pay QST on taxable goods and services acquired from outside Quebec that are used, consumed, or supplied within the province.

If your supplier didn’t charge QST — and isn’t registered under the Specified QST System (SQST) — you must calculate and remit it yourself.

Learning Insight

QST is a destination-based tax. If a taxable good or service is used in Quebec, Revenu Québec expects the province to receive the tax revenue — even if the seller is outside Quebec.

Step-by-Step: How to Self-Assess QST

Step 1 — Identify When Self-Assessment Applies

You must self-assess QST when you purchase:

• Goods from suppliers outside Quebec that don’t charge QST.

• Services performed outside Quebec but used or enjoyed in Quebec (for example, consulting, online ads, subscriptions).

• Intangible property such as downloadable software, cloud hosting, or streaming services.

You don’t self-assess when:

• The supplier is QST-registered and charges it on your invoice.

• The purchase is exempt or zero-rated.

Example:
A Quebec company buys $10,000 in equipment from an Ontario vendor that doesn’t charge QST. Because the goods are shipped to Montreal, the business must self-assess QST of 9.975 % = $997.50 and remit it to Revenu Québec.

Step 2 — Record the Purchase and Calculate QST

When entering the transaction in your accounting system, separate the QST portion clearly so that it appears in your QST Recoverable or Self-Assessed QST Payable accounts.
Your accounting software can calculate 9.975 % automatically on the taxable base.

If the purchase is for business use, you can also record an equal Input Tax Refund (ITR) entry, allowing the transaction to net to zero when you file your return.

Step 3 — Report on Your QST Return

When filing your QST return through Mon dossier pour les entreprises:

1. Include the self-assessed QST under “QST to remit.”

2. Claim the same amount as an Input Tax Refund (ITR) if the purchase is for business purposes.

If a purchase is partly personal, claim only the business-use portion.

Learning Insight

Failing to self-assess doesn’t always result in an immediate penalty — but during an audit, Revenu Québec can demand full payment with interest and may disallow your ITRs.

Step 4 — Digital and Online Purchases

Foreign suppliers of digital services (for example, Google Ads, Shopify, or Zoom) may already be registered under the Specified QST System (SQST) and charge QST directly.

If they don’t, you must self-assess. Check your invoices:

• Standard QST registration numbers end in TQ0001.

• SQST numbers begin with C (e.g., C0000123456).

If no number appears, you must self-assess the QST.

Step 5 — Keep Supporting Documentation

Maintain:

• Supplier invoices showing no QST charged.

• Proof that goods or services were used in Quebec.

• Self-assessment calculations.

• Copies of filed QST returns and confirmation numbers.

These documents protect you in the event of an audit.

Common Mistakes to Avoid

• Ignoring QST on inter-provincial or foreign purchases.

• Assuming GST covers all obligations.

• Forgetting to claim the offsetting Input Tax Refund.

• Failing to verify supplier QST registration.

• Treating digital services as automatically exempt.

Learning Insight

Revenu Québec and the CRA exchange data from banks and payment processors. Large out-of-province or online purchases are easily traceable — self-assess before they assess you.

Real Quebec Business Example

A Montreal marketing firm purchased $50,000 in U.S. online advertising and didn’t self-assess QST. During an audit, Revenu Québec charged $4,987.50 in unpaid tax plus interest.
After Mackisen CPA implemented proper self-assessment and ITR tracking, future filings became compliant and fully recoverable.

Lesson: Check every supplier invoice for QST status and self-assess where required.

Compliance Checklist

Do

• Verify whether each supplier charges QST.

• Self-assess on taxable goods and services used in Quebec.

• Claim ITRs for legitimate business purchases.

• Record self-assessed QST in your accounting system.

• Keep documentation for six years.

Don’t

• Ignore online or cross-province purchases.

• Forget to remit when supplier is unregistered.

• Mix personal and business expenses.

• Assume digital purchases are tax-free.

Mackisen Strategy

At Mackisen CPA Montreal, we help businesses stay compliant by:

1. Reviewing supplier lists to identify unassessed QST purchases.

2. Calculating and reporting self-assessed QST correctly.

3. Automating use-tax tracking in accounting software.

4. Preparing documentation that stands up to Revenu Québec audits.

We ensure your business meets every QST obligation — without surprises or penalties.

Why Mackisen

With over 35 years of combined CPA expertise, Mackisen CPA Montreal helps Quebec businesses master QST compliance, from collection and filing to self-assessment. We provide clarity, accuracy, and peace of mind.