GST QST Calculator

How Quebec sales tax (GST and QST) works

In Quebec, taxable sales, property leases, and customer services are subject to two distinct consumption taxes: the federal Goods and Services Tax (GST) administered by the Canada Revenue Agency and the Quebec Sales Tax (QST) administered by Revenu Québec. For the 2026 tax year, the combined sales tax rate in Quebec sits at exactly 14.975%, consisting of a 5.0% federal levy alongside a 9.975% provincial levy.

Whether you are invoicing corporate clients in Montreal, validating consumer receipts in Quebec City, or estimating retail margins, calculating both taxes accurately is vital for regulatory compliance. If you offer promotional markdowns before taxes are assessed, you can establish baseline net totals with our discount calculator. Similarly, if you manage international or multi-province supplies across Canada and abroad, our multi-jurisdiction GST calculator covers nationwide rates, while small business owners calculating payroll wage allocations alongside tax remittances can turn to the gross pay calculator. Self-employed contractors evaluating cross-border North American obligations can also reference our 1099 tax calculator.

Mathematical formulas for GST and QST

A common point of confusion among buyers and out-of-province vendors stems from Quebec's historical tax structure. Prior to January 1, 2013, QST was calculated on a compounded subtotal that already included federal GST. That legacy tax-on-tax mechanism was eliminated permanently on January 1, 2013. Under current rules, both taxes are calculated independently and directly against the pre-tax selling price.

1. Forward calculation: Adding taxes to a net amount

When you have the pre-tax net subtotal ($N$), apply the statutory rates directly:

Each tax amount is rounded to the nearest cent (half-cent or greater rounds up). For instance, on a $200.00 pre-tax purchase:

• Federal GST: $\$200.00 \times 0.05 = \$10.00$
• Provincial QST: $\$200.00 \times 0.09975 = \$19.95$
• Total sales tax: $\$10.00 + \$19.95 = \$29.95$
• Gross invoice total: $\$200.00 + \$29.95 = \$229.95$

2. Reverse calculation: Extracting pre-tax base from a gross total

When a price tag, restaurant bill, or retail checkout total already includes all applicable sales taxes, you must reverse the combined rate to discover the net selling price. Dividing by 1.14975 reveals the net base:

Once the net base is determined, federal GST (5%) and provincial QST (9.975%) are computed from that net base:

• Worked example: On a tax-inclusive retail total of $114.98, the net base is $\$114.98 \div 1.14975 = \$100.00$.
• Federal GST component: $\$100.00 \times 0.05 = \$5.00$.
• Quebec QST component: $\$100.00 \times 0.09975 = \$9.98$ (rounded from $9.975).
• Total sales tax extracted: $\$5.00 + \$9.98 = \$14.98$.

Canadian sales tax structure comparison (2026)

Canada operates three distinct sales tax regimes across provinces and territories. Quebec is unique because it maintains its own provincial administration (Revenu Québec) collecting both its provincial tax and the federal GST on behalf of Ottawa. Understanding this context helps clarify how Quebec compares with neighboring provinces:

Input tax credits (ITCs) and input tax refunds (ITRs) for businesses

Registered businesses in Quebec collect GST and QST on their commercial taxable sales. However, businesses generally do not bear the ultimate burden of these taxes on their legitimate commercial operations. Instead, registered companies recover sales taxes paid on business inputs through two parallel mechanisms:

1. Input Tax Credits (ITCs): Federal mechanism that reimburses the 5.0% GST paid on commercial purchases, inventory, office leases, equipment, and operating expenses.
2. Input Tax Refunds (ITRs): Provincial Quebec mechanism that reimburses the 9.975% QST paid on valid commercial expenditures.
3. Net Remittance: At the end of each reporting period (monthly, quarterly, or annually), the registrant offsets taxes collected against ITCs and ITRs paid. If taxes collected exceed taxes paid, the net balance is remitted to Revenu Québec. If taxes paid exceed collections, the business receives a refund.

Frequently asked questions