If you’ve ever stared at a Quebec receipt and wondered how the final total got there, you’re not alone. Whether you’re a small business owner, a freelancer, or just curious, understanding how GST and QST are calculated can save you both time and money.

Current GST rate in Canada: 5% ·
Current QST rate in Quebec: 9.975% ·
Total combined tax rate in Quebec: 14.975% ·
Year of these rates: 2026 ·
Effective date of QST rate: January 1, 1994

Quick snapshot

1Confirmed facts
2What’s unclear
  • Future rate changes after 2026 not announced
  • Possible federal election impacts on GST rate
  • Rounding differences between one-step and two-step methods can cause cent-level discrepancies
  • Businesses with older cash registers may need to round rates to 9.97% or 14.97%
3Timeline signal
  • GST introduced in 1991 at 7%
  • QST introduced in 1992
  • Current rates stable since 2013
4What’s next
  • Use the formulas below to calculate accurately
  • Check official sources for any rate updates

Six key facts, one pattern: Quebec’s tax system combines a federal rate (GST) and a provincial rate (QST) into a single blended calculation — but how you combine them depends on your cash register’s capabilities.

Label Value
GST rate (federal) 5%
QST rate (Québec) 9.975%
Combined rate in Québec 14.975%
Date rates take effect Current as of 2026
Official source for GST Canada Revenue Agency
Official source for QST Revenu Québec

How to Calculate GST and QST?

What are the current GST and QST rates?

How do you add taxes to a price?

  • One-step method (if your cash register supports three decimals): multiply the pre-tax price by 1.14975. Revenu Québec (official guidance) explains this as the combined rate calculation.
  • Two-step method (standard for most registers): first multiply by 1.05 (GST), then multiply that subtotal by 1.09975 (QST).
  • Example: For a $100 item, one-step gives $114.975 (before rounding); two-step gives the same result ($100 × 1.05 = $105. Then $105 × 1.09975 = $115.47375? Wait, that’s not identical. Revenu Québec notes that the two-step method calculates GST on the sale price first, then QST on the same sale price — not on the GST-inclusive amount. So correct two-step: GST = $100 × 0.05 = $5; QST = $100 × 0.09975 = $9.975; total = $100 + $5 + $9.975 = $114.975. Both methods give the same total when done correctly.
The upshot

Quebec businesses face a choice: one-step for registers that handle three decimals, two-step for standard cash drawers. The total tax collected is identical — but a rounding error can cost you a cent per transaction.

The implication: The two-step method is simpler for manual calculation, while the one-step factor reduces steps for computerized systems. Either way, the math must match official rates.

Quebec businesses must decide between one-step and two-step calculation; the total tax is identical but rounding rules require attention.

What Is the Quick Method to Calculate GST and QST?

How does the quick method work?

  • The quick method uses a single combined factor: 1.14975. Multiply the pre-tax price by this factor to get the total including both taxes.
  • This factor is derived from 1 + 0.05 + 0.09975 = 1.14975.
  • According to Revenu Québec (official guidance), this method is allowed when the cash register can calculate both taxes in one step.

What is the formula for the quick method?

  • Total price = Pre-tax price × 1.14975
  • For GST only: Total = Pre-tax price × 1.05
  • For QST only: Total = Pre-tax price × 1.09975

Why this matters: The quick method saves time and reduces errors — but only works if your point-of-sale system supports three-decimal multiplication. Otherwise, round to two decimals as allowed by Revenu Québec.

What Is the Reverse Formula to Calculate GST and QST?

How to find the pre-tax amount from a total?

  • Reverse formula for combined taxes: divide the total price by 1.14975.
  • Example: If you paid $114.98 (rounded), pre-tax price ≈ $114.98 / 1.14975 = $100.00
  • The Omni Calculator (online tax tool) confirms this reverse calculation method.

What is the reverse formula for GST only?

  • For GST only: Pre-tax amount = Total / 1.05
  • For QST only: Pre-tax amount = Total / 1.09975
  • These formulas are useful when you need to extract the original price from a tax-inclusive receipt, common in accounting and refund calculations.

The trade-off: Reverse calculation assumes the full combined rate was applied. If the vendor used a different method (e.g., two-step with rounding differences), your pre-tax figure may be off by a few cents.

How to Calculate Taxes on a Calculator?

How to manually calculate taxes without a calculator?

  • Manual method: Multiply the pre-tax amount by 0.05 for GST and by 0.09975 for QST, then add both to the original price.
  • In Google Sheets or Excel, use formulas: =A1*0.05 for GST and =A1*0.09975 for QST, as described by Juriclik (tax calculator site).
  • Rounding rules from Revenu Québec (official guidance): Only fractions of $0.005 or more round up; register rounding to 9.97% or 14.97% is allowed if hardware can’t handle three decimals.

What are the best online tax calculators for Quebec?

What to watch

Third-party calculators can be convenient, but always verify results against official sources — especially if the calculator uses rounded rates or outdated values.

The catch: Manual calculation is reliable but slow; online tools are fast but depend on the user selecting the correct rates. For business remittances, always use the exact official formulas.

How to Calculate the Amount Before Taxes?

How to calculate the original price before tax?

  • Pre-tax amount = Total price / (1 + tax rate). For combined GST+QST: divide by 1.14975.
  • Example: A total of $229.95 on a receipt → $229.95 / 1.14975 = $200.00 pre-tax.
  • This is essential for accounting, especially when claiming input tax credits or preparing financial statements.

How to apply the reverse formula for pre-tax amount?

  • Step 1: Identify the total amount paid.
  • Step 2: Divide by the appropriate factor (1.14975 for Quebec combined).
  • Step 3: Round to two decimal places if needed.
  • According to Omni Calculator (financial tool), this reverse method works for any tax rate combination.

What this means: Knowing the pre-tax amount is not just an academic exercise — it’s the basis for GST/HST refunds, business expense tracking, and ensuring you’re not overpaying on taxable supplies.

Timeline of GST and QST Rates in Canada

  • 1991 — Federal Goods and Services Tax (GST) introduced at 7%.
  • 1992 — Québec Sales Tax (QST) introduced to replace provincial sales tax.
  • 2008 — GST rate reduced from 6% to 5%.
  • 2013 — QST rate increased to 9.975% as part of harmonization with GST.
  • 2026 — Current rates remain unchanged: GST 5%, QST 9.975%.

The rate stability since 2013 ensures predictability for businesses.

Clarity: Confirmed Facts vs. What’s Unclear

Confirmed facts

What’s unclear

  • Future rate changes after 2026 are not yet announced
  • Possible federal election impacts on GST rate are speculative
  • Rounding differences between one-step and two-step methods can cause cent-level discrepancies
  • Businesses with older cash registers may need to round rates to 9.97% or 14.97%

Use this calculator to determine the amount of tax that applies to sales in Canada.

— Canada Revenue Agency (federal tax authority)

You must use the rate of 9.975% to calculate QST if your cash register calculates GST and QST in two steps.

— Revenu Québec (Quebec tax authority)

Here are the methods to calculate the amount of a tax or a discount…

— Alloprof (Quebec educational resource)

For Quebec consumers and businesses, the choice between one-step and two-step calculation is clear: use the method that matches your point-of-sale hardware. The numbers don’t lie — but rounding can. Always refer to official rates from Canada Revenue Agency and Revenu Québec.

Related reading: Qu’est-ce que la taxe carbone ? Comment elle fonctionne · Comprendre la taxe carbone en Irlande et dans le monde

Additional sources

juriclik.com, taxcloud.com, youtube.com, revenuquebec.ca, wowa.ca

Frequently asked questions

What is the difference between TPS and TVQ?

In Quebec, TPS (Taxe sur les produits et services) is the French acronym for GST, and TVQ (Taxe de vente du Québec) is the French acronym for QST. They are the same taxes with different names.

Are the tax rates different for businesses?

No, the GST and QST rates are the same for all consumers and businesses in Quebec. However, businesses may be eligible for input tax credits to recover the GST/QST they paid on expenses.

Do I need to include taxes in advertised prices?

In Quebec, prices must be displayed including GST and QST (taxes included) for most consumer goods and services, unless the business explicitly states that taxes are extra.

How often do GST and QST rates change?

Rate changes are rare. The GST has been at 5% since 2008, and the QST at 9.975% since 2013. Any future changes would be announced by the federal or provincial government.

Can I use the quick method for all transactions?

The quick method (one-step) is allowed only if your cash register can handle three-decimal numbers. Otherwise, you must use the two-step method or round as permitted by Revenu Québec.

What happens if I over-collect taxes?

If you over-collect GST or QST from customers, you must remit the excess to the tax authorities. Keeping over-collected amounts can result in penalties. Contact Revenu Québec for guidance.

How do I calculate taxes on a refund?

To calculate the tax component of a refund, use the reverse formula: divide the refund amount by 1.14975 (for Quebec) to get the pre-tax portion, then multiply by the respective tax rates to determine GST and QST refund amounts.

Where can I find the official tax rates for other provinces?

Visit the Canada Revenue Agency (federal authority) for a complete list of GST/HST rates by province.