GST/QST Declaration for Businesses: Step-by-Step Practical Guide - CPA Firm in Montreal

Introduction
For any business in Quebec, the declaration of GST (Goods and Services Tax) and QST (Quebec Sales Tax) is a legal obligation and a cornerstone of tax management. An error or delay can result in penalties, interest, and costly audits by Revenu Québec or the Canada Revenue Agency (CRA).

At Mackisen CPA Montreal, we guide entrepreneurs step-by-step to accurately and confidently file their GST/QST returns. This practical guide outlines each step of the process— from sales collection to electronic submission— to ensure compliance and optimize your cash management.

1. Understand your tax obligations

A. When to register for GST/QST:
You must register as soon as your taxable sales exceed $30,000 over a period of 12 consecutive months. You may also voluntarily register before reaching this threshold to claim your tax credits/refunds on your expenses.

B. Frequency of declarations:

2. Gather your accounting data

Before filling out your return, ensure you have the following documents:

• Total taxable sales (before tax) for the period.

• Amount of GST (5%) and QST (9.975%) collected from customers.

• Amount of GST/QST paid on your business purchases (supplier invoices).

• Tax credits and refunds to claim (ITC/RTI).

• Bank statements and cash reports.

Mackisen Tip: Use accounting software (QuickBooks, Sage, Xero) to automate these calculations and avoid manual errors.

3. Calculate your taxes owed

Step 1 – Calculate the GST and QST collected

Add up all taxes charged to your customers:

• GST = 5% of the amount before tax.

• QST = 9.975% calculated on the amount including the GST.

Example:
Price before tax: $1,000
GST (5%): $50
QST (9.975% on $1,050): $104.74
Total to charge: $1,154.74

Step 2 – Calculate your tax credits/refunds

Add up the GST/QST paid on your eligible expenses:

• Input tax credit (ITC) for GST.

• Input tax refund (RTI) for QST.

You can claim them on:

• Commercial rent.

• Supplies and professional services.

• Software, hardware, equipment.

• Advertising and transportation costs.

Step 3 – Calculate the net balance to remit or receive

Formula:

GST/QST collected – ITC/RTI = Net amount to remit or refund.

Example:

• GST collected: $5,000

• QST collected: $10,475

• GST paid (ITC): $3,200

• QST paid (RTI): $6,400

Result:
Amount to remit: (5,000 + 10,475) - (3,200 + 6,400) = $5,875

4. Fill out your return (GST/QST)

A. GST Return — Canada Revenue Agency (CRA)

• Log in to your My Business Account portal (canada.ca/my-business-account).

• Fill out Form GST34 (or GST62 for paper version).

  • Line 101: Total sales before tax.

  • Line 103: GST collected.

  • Line 106: ITCs claimed.

  • Line 109: Net amount to remit (or refund).

B. QST Return — Revenu Québec

• Log in to My File for Businesses (revenuquebec.ca/mon-dossier).

• Fill out Form FPZ-500-V:

  • Line 201: Total sales (before tax).

  • Line 202: QST collected.

  • Line 208: RTIs claimed.

  • Line 209: Net amount to remit (or refund).

Submit your return online and keep the transmission confirmation.

5. Make payment or claim a refund

• If the balance is positive, pay the GST/QST owed by the deadline to avoid penalties.

  • Payment by online banking, My File, or pre-authorized debit.

• If the balance is negative, a refund will be issued by direct deposit.

Processing times:

• Online: 5 to 10 business days.

• By mail: up to 4 weeks.

6. Keep your records and supporting documents

Keep for at least 6 years:

• Sales and purchase invoices with GST/QST registration numbers.

• Cash reports, accounting books, and bank statements.

• Electronic confirmations of your returns.

In case of an audit, Revenu Québec will require these proofs to validate your ITCs/RTIs.

7. Prevent errors and penalties

Common errors:

• Confusing exempt and zero-rated sales (0% vs non-taxable).

• Claiming an ITC/RTI without a valid invoice.

• Forgetting to include the GST in the calculation of the QST.

• Filing delays resulting in interest.

Applicable penalties:

• 5% of the unpaid balance + 1% per month (up to 12 months) under the Quebec Tax Administration Act, article 59(3).

8. Complete example of GST/QST return

Case law and compliance
Case law confirms the responsibility of businesses in terms of compliance:

• Canderel Ltd. v. Canada (SCC, 1998) — the declaration must reflect the commercial reality.

• Hickman Motors Ltd. v. Canada (SCC, 1997) — the burden of proof is on the taxpayer.

• Asbestos Mines of Quebec Ltd. (SCC, 2001) — Revenu Québec has full audit authority.

These decisions remind that any error or omission in your returns can lead to reassessment.

9. Simplify your returns with a CPA

At Mackisen CPA Montreal, we:

1. Verify your sales and purchase records.

2. Calculate your net GST/QST balance.

3. Prepare and submit your electronic forms.

4. Help you claim all your eligible ITCs/RTIs.

5. Provide comprehensive defense in case of an audit.

Mackisen Service Hub: Comprehensive GST/QST Management
Our Mackisen Service Hub offers a turnkey solution:

• GST/QST registration and account setup.

• Monthly, quarterly, or annual returns.

• Verification and optimization of input credits.

• Archiving and documentation ready for audit.

Our bilingual CPAs and tax professionals— graduates of McGill, Université de Montréal, and Concordia — guarantee accurate, timely, and compliant returns.

Real example
A SME in Laval was manually filing its returns and forgot to claim $15,000 in ITCs/RTIs on its expenses. Mackisen CPA reconstituted the records, produced corrected returns, and obtained a full refund, while automating the process for subsequent periods.

Why Mackisen
With over 35 years of combined experience, Mackisen CPA Montreal ensures the compliance of your GST/QST returns and the peace of mind of your business.

When you file with Mackisen, every cent is justified, every form is accurate, and every tax period is mastered—from the initial calculation to the final confirmation from Revenu Québec.