Filing GST/QST returns is a mandatory and recurring obligation for every business operating in Quebec. Whether you file monthly, quarterly, or annually, preparing a clean and accurate return requires organization, documentation, and a solid understanding of sales tax rules. Errors in your GST/QST return can lead to refund delays, penalties, interest, and even audits. Many businesses struggle because their records are incomplete, their POS systems are misconfigured, or they underestimate the importance of reconciling tax amounts regularly. This guide provides a comprehensive 10-step checklist to help businesses prepare a smooth, accurate, and audit-ready GST/QST return every time.

The goal of a strong GST/QST filing system is to ensure that every dollar of tax collected, every allowable input tax credit, and every adjustment is fully supported and consistent with your financial records. A disciplined checklist helps prevent common errors and improves overall compliance.

LEGAL AND REGULATORY FRAMEWORK

GST is governed by the federal Excise Tax Act, while QST is administered by the Quebec Taxation Act. Businesses registered for GST and QST must collect, report, and remit tax on all taxable supplies. Filing deadlines depend on the reporting frequency assigned to the business. Revenu Québec administers both GST and QST in Quebec, making accuracy and documentation essential. Businesses must retain invoices, receipts, credit notes, contracts, and supporting documents for at least six years in case of audit.

Your GST/QST return must reflect accurate taxable sales, exempt sales, zero-rated sales, tax collected or collectible, input tax credits, and adjustments. Each return must align with your bookkeeping and bank records, as discrepancies raise compliance concerns.

KEY COURT DECISIONS

Courts consistently uphold that taxpayers are responsible for filing accurate GST/QST returns and keeping proper documentation. Several rulings confirm that missing invoices, incomplete tax details, or inconsistent reporting justify reassessments. Judges have ruled that taxpayers cannot rely on estimates or verbal explanations; they must produce clear evidence supporting each amount reported.

In refund-related decisions, courts upheld Revenu Québec’s right to withhold refunds until proper documentation is provided. Businesses that failed to maintain clean records or follow filing procedures faced delays, denied credits, or penalties. These rulings highlight the importance of using a structured, repeatable filing checklist.

WHY CRA AND REVENU QUÉBEC TARGET THESE ISSUES

Revenu Québec and CRA closely review GST/QST filings because errors often indicate deeper accounting problems. Common audit triggers include high refunds, unexplained changes in sales patterns, large input tax credits, mismatches between sales tax returns and income tax filings, or incomplete supporting documents. Retailers, contractors, online sellers, and consultants often face reviews because of manual processes, multiple staff handling transactions, or inconsistent invoicing.

A well-maintained checklist reduces these risks and ensures a smooth filing process every period.

THE 10-STEP GST/QST FILING CHECKLIST

1. Reconcile total sales for the period
   Confirm that your sales ledger, bank deposits, and POS reports match. Identify taxable, exempt, and zero-rated sales separately.

2. Verify GST and QST collected
   Ensure the tax amounts collected match system calculations and were recorded correctly on each invoice.

3. Review input tax credit documentation
   Verify that all supplier invoices contain required GST/QST numbers, descriptions, and tax amounts.

4. Separate eligible and non-eligible expenses
   Exclude personal expenses, exempt expenses, and incomplete receipts from your CTI claims.

5. Match refunds, returns, and credit notes
   Ensure adjustments are documented and reflected properly in your GST/QST return.

6. Check for missing invoices or receipts
   Request duplicates from suppliers before filing; missing documents can cause denied credits.

7. Reconcile your GST/QST control accounts
   Match tax collected and tax paid with your general ledger to ensure accuracy.

8. Confirm your remittance deadline and frequency
   Late filings trigger penalties. Align cash flow planning with your GST/QST due dates.

9. Review your return for consistency
   Ensure your GST/QST return aligns with your financial statements and prior periods.

10. Maintain an audit-ready file
    Organize invoices, summaries, ledgers, and bank statements for quick access if Revenu Québec requests information.

Following these steps every period helps create a predictable and compliant filing workflow.

MACKISEN STRATEGY

Mackisen CPA helps businesses implement structured GST/QST filing systems based on this 10-step checklist. We review your bookkeeping, POS configuration, tax codes, invoices, and bank reconciliations to ensure accuracy. Our team prepares GST/QST returns, identifies discrepancies early, and prevents issues that may lead to audits. We also create customized filing templates and internal checklists for your staff, ensuring consistent reporting each period.

For businesses experiencing ongoing challenges, Mackisen performs GST/QST compliance reviews, corrects errors from past periods, and manages refund submissions. We also support businesses undergoing Revenu Québec audits by preparing documentation and negotiating adjustments when necessary.

REAL CLIENT EXPERIENCE

A retail business repeatedly encountered GST/QST discrepancies because staff used incorrect tax settings in their POS system. Mackisen reconfigured their system, prepared a filing checklist, and trained staff. Their returns are now error-free.

A consultant failed to claim eligible input tax credits because invoices were disorganized. Mackisen rebuilt their filing system, captured missing credits, and optimized future filings.

A contractor misclassified several exempt and taxable activities, resulting in inconsistent filings. Mackisen corrected the classifications, updated procedures, and prevented a potential audit reassessment.

COMMON QUESTIONS

What happens if I file my GST/QST return late?
Revenu Québec charges penalties and daily interest. Repeated late filings increase audit risk.

Do I need a checklist if I use accounting software?
Yes. Software helps, but human oversight is necessary to catch misclassifications and missing documents.

Can I request a refund if I paid too much GST/QST?
Yes. Adjustments can be filed if documentation supports the correction.

How often should I reconcile GST/QST accounts?
Monthly reconciliations are recommended even for quarterly or annual filers.

Do small mistakes trigger audits?
Sometimes. Minor inconsistencies in multiple periods can alert Revenu Québec’s systems.

WHY MACKISEN

Avec plus de 35 ans d’expérience combinée, Mackisen CPA Montréal aide les entreprises à produire des déclarations TPS/TVQ conformes, exactes et sans stress. Whether you're filing monthly, quarterly, or annually, our structured systems and expert supervision protect you from reassessments, penalties, and audit exposure.