GST/QST Deadlines in Quebec: Filing Frequencies, Due Dates, Penalties, and What Happens If You Miss a Deadline

Introduction

Missing GST/QST deadlines is one of the fastest ways a business in Quebec ends up with penalties, interest, and automated audit reviews. Whether you file annually, quarterly, or monthly, every filing has a strict due date — and Revenu Québec enforces them aggressively.
Many entrepreneurs misunderstand their assigned frequency, forget to remit on time, or assume they can delay payment until cash flow improves. These mistakes lead to costly consequences.
This guide explains every GST/QST deadline, how filing frequencies are assigned, what happens when you file late, and how to avoid penalties.

Legal and Regulatory Framework

Under the Excise Tax Act (GST) and the Quebec Taxation Act (QSTA):

• Filing frequency is determined by your total annual taxable revenues.

• Remittances are due by the prescribed due date — even if you haven’t collected the tax.

• Registrants must maintain accurate records, reconcile sales/expenses, and remit collected GST/QST on time.

• Late filings trigger penalties under ETA s.280 and QSTA s.28.

• Record-keeping violations fall under ETA s.286 and QSTA s.24.

Filing frequencies:

• Annual: Revenues under $1.5M

• Quarterly: Revenues $1.5M to $6M

• Monthly: Revenues over $6M

Due dates:

• Monthly/Quarterly filers: One month after the end of the reporting period

• Annual filers (sole proprietors): June 15

• Annual remittance due: April 30

Key Court Decisions

Courts have confirmed that:

• Interest applies even when tax was never collected from customers.

• Financial hardship does not excuse late remittance.

• Revenu Québec may deny ITCs/ITRs for repeated late filers due to bookkeeping deficiencies.

• The burden is on the taxpayer to ensure timely filing — system errors, staff changes, or miscommunication are not valid defences.

These decisions show the strict enforcement of GST/QST deadlines.

Why CRA and Revenu Québec Target These Issues

Late filings are a major compliance red flag because:

• They often indicate poor bookkeeping or cash flow issues.

• Businesses that file late frequently misreport revenue or ITCs.

• Late remittances may suggest that GST/QST collected from clients was used for operating expenses.

• Repeated late filings automatically trigger audit risk.

• Late filers often claim large adjustments or refunds, which authorities review more closely.

Industries most affected include small retail, food services, construction, online sellers, contractors, and freelancers.

Mackisen Strategy

We help businesses avoid penalties by installing a complete filing and cash flow system.

1. Deadline Tracking & Automation

We implement:

• Calendar reminders

• Filing checklists

• Automated QuickBooks reports

• Alerts based on your frequency

2. Filing Frequency Review

We determine whether:

• Your assigned frequency is correct

• A change is beneficial

• Annual filing creates cash flow advantages

• Quarterly filing better aligns with revenue cycles

3. GST/QST Reconciliation

We prepare:

• Monthly and quarterly reconciliations

• Adjusted ITC/ITR logs

• Sales and expense summaries

• Prior-period correction entries

4. Late Filing Corrections

If you're already late, we handle:

• Filing all missing periods

• Interest and penalty reduction requests (case-dependent)

• Communications with Revenu Québec

• Arrangement or correction plans

5. Audit Defence

If lateness triggers a review, we manage:

• Full document submissions

• Legal arguments with statutory references

• Revenue reconciliation proof

• Negotiations for penalty relief where available

Real Client Experience

A Montreal retailer missed five consecutive quarterly GST/QST deadlines. Revenu Québec assessed more than $7,000 in interest and penalties.
Mackisen reconstructed all sales, filed all returns, and negotiated a partial interest reduction by demonstrating system errors and implementing new compliance controls.
This case shows that even severe late filings can be corrected with proper strategy.

Common Questions

1. What if I file late but have no tax owing?
You may still face penalties for late filing, depending on your situation.

2. Can I change my filing frequency?
Yes — under certain conditions, but approval is required.

3. Do I still owe GST/QST if my customers never paid me?
Yes, unless the debt becomes officially uncollectible.

4. What happens if I miss multiple periods?
Revenu Québec may freeze refunds, demand records, or initiate an audit.

Why Mackisen

With more than 35 years of combined CPA experience, Mackisen CPA Montreal helps businesses stay compliant while recovering the taxes they’re entitled to. Whether you’re filing your first GST/QST return or optimizing multi-year refunds, our expert team ensures precision, transparency, and protection from audit risk.

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