Whether you are a freelancer, contractor, retailer, or growing corporation, knowing exactly when your GST/QST return and payment are due is essential. Missing a filing deadline triggers penalties, interest, refund delays, and even audit scrutiny. But filing deadlines depend on your assigned reporting period, which varies from business to business. This guide explains the GST/QST reporting periods, how deadlines are determined, and how to avoid late filings. Understanding your deadlines is one of the most important parts of Quebec sales tax compliance. LEGAL AND REGULATORY FRAMEWORK Deadlines for GST/QST returns and payments come from: • the Excise Tax Act (GST) • the Quebec Taxation Act (QST) When you register for GST/QST, Revenue Québec assigns you a filing frequency based on your annual taxable revenue. Your return and payment are due at the same time. The three filing frequencies are: • Monthly • Quarterly • Annual KEY COURT DECISIONS Courts consistently affirm that: • filing deadlines are strict even one day late triggers penalties • interest accrues automatically after the due date • misunderstanding your filing frequency is not a defence • businesses must keep documentation organized by filing period • refund claims may be delayed if prior filings are late Judges emphasize that sales tax deadlines are a legal obligation, not an administrative preference. WHY BUSINESSES MISS DEADLINES Common reasons include: • confusion about filing frequency • bookkeeping delays • last-minute reconciliations • missing invoices • POS reports not matching accounting software • cash flow issues delaying payment • forgetting to file nil returns These issues often indicate deeper compliance weaknesses. WHAT IS THE GST/QST DEADLINES? 1. MONTHLY FILERS Monthly filers must file by the last day of the following month. Example: • January return → due February 28/29 • February return → due March 31 Monthly filing applies to: • large businesses (over $6M in annual revenue) • businesses that request it for faster refunds 2. QUARTERLY FILERS Quarterly filers must file by the last day of the month following the quarter. Quarter Period Filing Deadline Q1 Jan 1 – Mar 31 Apr 30 Q2 Apr 1 – Jun 30 Jul 31 Q3 Jul 1 – Sep 30 Oct 31 Q4 Oct 1 – Dec 31 Jan 31 This is the most common filing frequency for small and medium businesses. 3. ANNUAL FILERS Annual filers must file within three months after their fiscal year-end. Example: If year-end is December 31 → return is due March 31. However: • payment is also due within three months • if you owe tax, interest applies from that date • annual filing is allowed for smaller businesses (under $1.5M in revenue) SPECIAL CASES SELF-EMPLOYED INDIVIDUALS If you are self-employed: • GST/QST return is due three months after year-end • payment is due on the same date This is different from personal income tax, which allows later payment. SEASONAL BUSINESSES Filing frequency stays the same even when the business is temporarily closed. NEW BUSINESSES Your first filing deadline depends on the date you registered, not on the date you started operations. CHANGING FILING FREQUENCY You may request to change your frequency (monthly ↔ quarterly ↔ annual) if you meet revenue criteria. WHAT IF A DEADLINE FALLS ON A WEEKEND OR HOLIDAY? If the due date falls on: • a Saturday • a Sunday • a statutory holiday Then your deadline moves to the next business day. WHAT HAPPENS IF YOU MISS A DEADLINE? Consequences include: • late filing penalties • daily interest charges • refund delays or suspension • system flags for non-compliance • increased likelihood of audit selection Even if no tax is due, late filing still affects your risk profile. BEST PRACTICES TO NEVER MISS A DEADLINE • set calendar reminders • reconcile GST/QST monthly even if filing quarterly • organize receipts early • avoid last-minute filing • schedule time each period for tax preparation • monitor Mon Dossier for reminders or notices • keep POS and accounting reports synchronized MACKISEN STRATEGY Mackisen CPA helps businesses stay compliant by setting up GST/QST filing calendars, automated reminders, and efficient reconciliation systems. We manage deadlines, prepare returns, organize documentation, and communicate with Revenu Québec on your behalf. We also help businesses change their filing frequency to one that better suits their cash flow and workload. REAL CLIENT EXPERIENCE A software company repeatedly filed late due to rapid growth. Mackisen built monthly reconciliation tools and eliminated every late return. A contractor misunderstood their quarterly deadline and missed it. Mackisen corrected past filings and set up calendar alerts. A retailer with a high refund cycle switched to monthly filing and improved cash flow dramatically. COMMON QUESTIONS Is the GST/QST payment due the same day as the filing? Yes both are due on the deadline. Can I file early? Yes. Filing early is recommended. Do nil returns need to be filed? Absolutely failure to file triggers penalties. Does Revenue Québec send reminders? Sometimes, but do not depend on them. WHY MACKISEN With more than 35 years of combined CPA experience, Mackisen CPA Montreal ensures your GST/QST filings are always on time and fully compliant. Our systems prevent penalties, reduce audit risk, and keep your account in excellent standing.