Insights
Nov 12, 2025
Mackisen
Top 7 GST/QST (TPS/TVQ) Filing Mistakes Quebec Businesses Must Avoid — How to Stay Compliant and Penalty-Free
Avoid the most common GST/QST (TPS/TVQ) and HST errors that cost Quebec businesses thousands every year. Learn what Revenu Québec and CRA auditors look for, how to correct mistakes before they escalate, and how Mackisen CPA Montreal can keep your filings accurate, compliant, and stress-free.
Why Quebec Businesses Get Caught in GST/QST (TPS/TVQ) Filing Errors
Filing your GST/QST (TPS/TVQ) and HST returns is more than just reporting taxes — it’s a legal obligation under both the Excise Tax Act (CRA) and the Tax Administration Act (ARQ). Each year, Revenu Québec identifies thousands of filing errors that lead to reassessments, delayed refunds, and heavy penalties.
According to Le Journal de Montréal and Les Affaires, the most frequent audit triggers in 2024 were late filings, inconsistent data between CRA and Revenu Québec returns, and missing records. Once flagged, your business can face interest charges of 6% per year, penalties up to 25% of unpaid tax, and even account garnishment under ITA Section 222.
Understanding and avoiding these seven critical errors can protect your business, your reputation, and your bottom line.
Mistake 1 — Missing the Filing Deadline
This is the number-one mistake among Quebec entrepreneurs. Many assume that filing late is minor, but both Revenu Québec and the CRA apply automatic late-filing penalties:
5% of your unpaid balance, plus 1% per month for up to 12 months.
Daily compounding interest under both the CRA Excise Tax Act and ARQ Tax Administration Act.
Even if you can’t pay the full balance, always file your GST/QST (TPS/TVQ) and HST returns on time. Mackisen CPA Montreal helps clients set up automated calendar reminders and direct electronic payments to avoid late submissions.
Mistake 2 — Incorrectly Charging or Calculating Tax Rates
Many small businesses misapply GST and QST because of confusion over rates and exemptions.
GST: 5% across Canada.
QST: 9.975%, applied after GST on the subtotal.
Incorrect sequencing or using outdated rates can lead to undercollection or overcollection. Both scenarios result in penalties and re-filings. Mackisen CPA Montreal reviews invoices and accounting systems to ensure every sale applies taxes correctly.
Mistake 3 — Not Claiming All Input Tax Credits (ITCs) and Refunds (ITRs)
Missing eligible credits means losing money. Businesses can recover GST/QST paid on expenses such as:
Rent and utilities.
Professional fees.
Advertising and supplies.
Equipment and software purchases.
Many owners forget to claim ITCs or ITRs due to poor documentation or categorization. CRA and ARQ require receipts with clear tax amounts and supplier registration numbers. Mackisen CPA Montreal reconciles these automatically, ensuring no refund is missed.
Mistake 4 — Mixing Business and Personal Transactions
Using the same account for business and personal expenses creates confusion during audits. It can also invalidate tax deductions and credits. Revenu Québec auditors look for inconsistencies in business-to-personal transfers, which often result in reassessments.
Separate your accounts completely:
One bank account for operations.
One trust account for GST/QST (TPS/TVQ).
No personal expenses through business credit cards.
Our CPA team helps structure accounts properly and trains staff to maintain clean records that stand up to audit scrutiny.
Mistake 5 — Filing Inconsistent Returns with CRA and ARQ
Because the CRA handles GST/HST and Revenu Québec handles QST, both systems compare your numbers automatically. If your sales, credits, or tax collected differ between filings, expect an audit.
For example: if you report $200,000 in taxable sales to CRA and $190,000 to Revenu Québec, their systems flag a “variance.” Even an honest mistake can suspend refunds or trigger penalties.
Mackisen CPA Montreal ensures all data reconciles between CRA’s My Business Account and Revenu Québec’s Mon dossier pour les entreprises before submission.
Mistake 6 — Not Keeping Receipts and Records for Six Years
Both CRA and ARQ can audit your business up to six years after your filing. Under Section 230 of the Income Tax Act and Section 94 of the Tax Administration Act, businesses must retain complete books and records, including:
Sales and purchase invoices.
Bank statements.
E-file confirmations.
ITC/ITR backup.
Failure to provide proof can lead to disallowed credits, even if your claims were legitimate. Mackisen CPA Montreal uses cloud-based accounting tools that automatically store and categorize receipts, ensuring you’re always audit-ready.
Mistake 7 — Not Consulting a CPA Before Filing
Many entrepreneurs try to file alone or rely solely on accounting software. While software automates math, it doesn’t catch legal inconsistencies, missing exemptions, or reconciliation errors between CRA and ARQ filings.
A CPA ensures:
Correct application of GST/QST and HST rates.
Consistent data between agencies.
Audit-proof documentation.
Timely filing and accurate payments.
Mackisen CPA Montreal provides bilingual CPA and tax-law expertise, protecting clients from costly government reviews.
What the Media Says — CRA and ARQ Are Watching Closely
Recent La Presse headlines confirm that “Revenu Québec intensifie ses vérifications.” (Revenu Québec is intensifying its audits.)
Journalists report that Revenu Québec now uses AI-powered data matching to identify risky businesses instantly. The CRA also launched a joint audit initiative for GST/QST (TPS/TVQ) and HST compliance, sharing data across federal and provincial levels.
The Journal de Montréal recently profiled a Laval café that lost $8,000 in penalties for failing to reconcile its QST refunds, even though it had filed. Another case involved an online seller whose inconsistent CRA and ARQ returns resulted in a full audit.
The lesson is clear: accuracy and timing matter more than ever.
Mackisen CPA Montreal — Your Partner for Error-Free Filing
Mackisen CPA Montreal prevents costly mistakes before they happen. Our bilingual CPA team combines accounting precision with legal expertise to ensure full compliance with both CRA and Revenu Québec.
We handle:
GST/QST (TPS/TVQ) and HST registration and setup.
Monthly or quarterly reconciliations.
Filing and payment through Mon dossier and My Business Account.
Audit preparation and representation.
Voluntary disclosure for past mistakes.
With over 35 years of combined CPA experience, we make tax compliance simple, transparent, and penalty-free.
Why Businesses Trust Mackisen CPA Montreal
100% filing accuracy across CRA and ARQ systems.
Faster refunds through automated reconciliation.
Guaranteed compliance with Excise Tax Act and Tax Administration Act.
Audit defense backed by experienced CPAs and tax lawyers.
Personalized service for businesses in every sector — retail, tech, construction, and professional services.
We don’t just fix mistakes we prevent them entirely.
Key Takeaways for Quebec Business Owners
File every GST/QST (TPS/TVQ) and HST return on time, even with a balance due.
Keep six years of organized receipts and invoices.
Reconcile sales and credits between CRA and ARQ every period.
Claim every eligible ITC and ITR to maximize refunds.
Use CPA oversight to ensure legal compliance and peace of mind.
Avoiding mistakes isn’t about luck — it’s about strategy. Partnering with Mackisen CPA Montreal ensures your GST/QST (TPS/TVQ) and HST filings are clean, compliant, and audit-proof.
