How to Determine if You Need to Register for QST (Quebec Sales Tax) — Montreal CPA Firm

Many entrepreneurs misunderstand when QST registration becomes mandatory, and this misunderstanding can cost thousands. Revenue Québec actively monitors businesses for signs that they exceeded the $30,000 threshold. When they detect non-registration, they impose retroactive tax, penalties, and interest. This guide explains how to determine if you need to register for QST and how to avoid costly surprises using Mackisen’s proven compliance framework.

Why QST Registration Matters
QST is mandatory once you exceed revenue thresholds. If you do not register in time, you may owe QST you never charged to customers, meaning you must pay it out of pocket. Additionally, ITRs (Input Tax Refunds) are denied for periods prior to registration.

Legal and Regulatory Framework
The Tax Administration Act outlines mandatory registration rules. Non-compliance can lead to forced registration, estimated assessments, penalties, and interest. Hickman Motors (1997) and Lac d’Amiante (2001) reinforce strict compliance expectations.

What Happens When You Don’t Register
Imagine running your business for two years, issuing invoices without tax. One day, RQ contacts you: “We note your revenues have exceeded $30,000. You were required to register two years ago.” They assess all uncollected QST retroactively — thousands of dollars — plus interest. Worse, you cannot go back to customers to recover it. The debt is yours.

Learning Section: Understanding the QST Threshold
Registration is mandatory when:
Taxable worldwide revenues exceed $30,000 in the last four consecutive quarters
Revenue exceeds $30,000 in a single quarter
You operate a regulated activity that requires registration regardless of revenue
Voluntary registration is often recommended to avoid surprises and claim ITRs.

SEO Learning: Primary and Secondary Keywords
Primary: QST registration Quebec, when to register QST, Quebec sales tax registration.
Secondary: QST threshold rules, register for TVQ Quebec, Montreal CPA QST advice.

Documentation Section
Revenue tracking sheets
Invoices and contracts showing revenue
Bank statements showing deposits
Accounting system revenue reports
Sales summaries from e-commerce platforms
All must be kept for six years.

Common Mistakes
Assuming threshold applies only to Quebec clients
Not counting online or foreign revenue
Ignoring deposits received through Stripe or PayPal
Not registering GST at the same time
Believing QST is optional below $30,000
Failing to monitor revenue quarterly

Winning With Revenue Québec and Canada
Mackisen analyzes your revenue structure, verifies your threshold status, registers you correctly, configures your invoicing system, and protects you from late-registration assessments. We also adjust your accounting system to ensure accurate tracking going forward.

Mackisen Service Hub
We handle QST registration, GST registration, threshold monitoring, invoicing setup, documentation review, and compliance oversight.

Why Mackisen
With over 35 years of CPA and tax expertise, Mackisen CPA Montreal ensures correct registration, protects your ITRs, and keeps you free from retroactive QST assessments.