Quebec GST/QST Reverse Calculator

Split any Quebec total into the base price, 5% GST and 9.975% QST — or add both taxes forward. Parallel calculation, per Revenu Québec.

Quebec — GST 5% + QST 9.975%

AmountTax-inclusive total

Base price (before tax)$86.98

GST (federal 5%)$4.35

QST (9.975%)$8.68

Total tax (14.975%)$13.02

Total (tax included) $100.00

GST and QST are both calculated on the pre-tax price — parallel taxes, per Revenu Québec rules in force since January 1, 2013.

Official QST calculation rules — Revenu Québec

What this result means for you

Your $100.00 Quebec total splits into a $86.98 base price, $4.35 GST (5%) and $8.68 QST (9.975%) — both taxes calculated in parallel on the base, per Revenu Québec. The divisor for reverse work is 1.14975.

Stacked-tax trap: if QST were applied the pre-2013 way — 9.975% on the GST-inclusive amount — this sale would show $9.11 of QST instead of $8.68, overcharging $0.43. Spreadsheets and old tools that stack QST on top of GST repeat this error on every invoice.

Includes your calculation, the Quebec Magic Number (divide by 1.14975), and ready-to-paste Excel formulas. Pure client-side — no data leaves your browser.

Need another province? Use the Canada GST/HST Calculator for all 13 provinces →

How to Reverse Quebec GST and QST in 4 Steps

Enter the total

Type the tax-inclusive amount from your Quebec receipt or invoice (or a pre-tax amount in Add mode).

Keep Reverse mode on

Reverse is the default — it divides your total by 1.14975 to recover the base price.

Read the three lines

Base price, 5% GST and 9.975% QST appear separately — exactly how a Quebec invoice must show them.

Copy or download

Copy the breakdown or download the CSV with the Quebec Magic Number and Excel formulas.

QST vs HST: Why Quebec Is Different

Quebec is the only province with its own value-added tax, the Quebec Sales Tax, administered by Revenu Québec rather than the CRA. Unlike HST provinces — where the 5% federal GST and the provincial portion merge into one combined tax — Quebec keeps GST and QST as two separate taxes on every invoice. Both are calculated in parallel on the same pre-tax price: 5% GST plus 9.975% QST, an effective combined burden of 14.975%. Two taxes also means two registrations and two remittances for businesses selling into Quebec.

Why 9.975%? The 2013 Switch from Stacked to Parallel

Before 2013, QST was 9.5% but calculated on the GST-inclusive price — tax on tax. On January 1, 2013, Revenu Québec switched QST to a parallel calculation on the pre-tax price, and adjusted the rate to 9.975% so the total burden stayed identical: 1.05 × 9.5% = 9.975%. That is why Quebec's rate looks so odd — it is the old stacked rate translated into parallel form. Any tool or spreadsheet that still applies QST to the GST-inclusive amount is using the pre-2013 method and will overcharge.

Reverse Calculation: From a Quebec Total to the Base Price

When you hold a receipt showing only the final total, divide it by 1.14975 to recover the pre-tax price — that is the Quebec Magic Number, 1 plus the combined 14.975% rate. Then GST is 5% of that base and QST is 9.975% of the same base. Example: a $114.98 restaurant bill splits into a $100.00 base, $5.00 GST and $9.98 QST. Never subtract 14.975% from the total — subtracting percentages instead of dividing is the classic reverse-tax error and understates the base.

Selling Into or Out of Quebec: Who Charges QST?

QST follows place-of-supply rules: it applies to sales delivered into Quebec. Out-of-province and foreign sellers must register for QST once their sales to Quebec consumers exceed $30,000 over 12 months — Quebec pioneered this remote-seller registration in Canada. In the other direction, a Quebec business shipping to Ontario charges Ontario's 13% HST, not GST + QST. For every other province's rates and the cross-province rules, use the Canada GST/HST Calculator.

Common Quebec Sales Tax Mistakes

First: applying QST on top of the GST-inclusive amount — that is the pre-2013 stacked method; today both taxes apply to the pre-tax price, and stacking 9.975% overcharges every sale. Second: rounding QST to 10% — the legal rate is exactly 9.975%, and on large invoices the difference is real money. Third: merging GST and QST into one 14.975% line — Quebec invoices must show them separately because they are remitted to different authorities. Fourth: reverse-calculating by subtracting 14.975% instead of dividing by 1.14975.

Quebec GST/QST Calculator FAQ

Q1.How is QST different from HST?

HST is a single combined federal-provincial tax collected by the CRA. QST is Quebec's own separate tax, administered by Revenu Québec: invoices show GST 5% and QST 9.975% as two distinct lines, businesses register for the two taxes separately, and remittances go to two different authorities. The combined burden (14.975%) is close to Atlantic HST rates, but the mechanics are entirely different.

Q2.Do I charge QST to customers outside Quebec?

No. QST applies to supplies delivered into Quebec. If you ship from Quebec to Ontario, you charge Ontario's 13% HST; to Alberta, just 5% GST. Conversely, sellers outside Quebec must register for and collect QST once their sales to Quebec consumers pass $30,000 in a 12-month period.

Q3.Is Quebec QST 9.975% or 9.5%?

9.975% — and it has been since January 1, 2013. The 9.5% figure is the old rate from when QST was calculated on the GST-inclusive price. The switch to a parallel calculation kept the total burden identical (1.05 × 9.5% = 9.975%), which is exactly where the unusual 9.975% number comes from.

Q4.Is QST calculated on top of GST?

Not anymore. Since January 1, 2013, QST is calculated on the pre-tax price, in parallel with GST — not on the GST-inclusive amount. Applying 9.975% to the GST-inclusive price is the pre-2013 stacked method and overcharges by about 0.5% of the base on every sale.

Q5.Why is Quebec's combined sales tax 14.975%?

Because 5% GST plus 9.975% QST both apply to the same pre-tax price: 5 + 9.975 = 14.975%. A $100 purchase costs $114.98 in Quebec. The odd-looking QST rate preserves the exact tax burden of the old stacked system, so totals did not change when the calculation method did in 2013.

Q6.How do I reverse-calculate GST and QST from a Quebec total?

Divide the tax-inclusive total by 1.14975 to get the base price; GST is 5% of that base and QST is 9.975% of the same base. Example: $114.98 ÷ 1.14975 = $100.00 base, $5.00 GST, $9.98 QST. In Excel: =A2/1.14975 for the base, then =B2*5% and =B2*9.975%.

Q7.Do I need to register for QST?

Quebec businesses must register once taxable sales exceed $30,000 over four consecutive quarters — same threshold as GST. Sellers outside Quebec (including foreign digital businesses) must register under Quebec's specified system once sales to Quebec consumers exceed $30,000 in 12 months. Below the threshold, registration is optional but lets you claim input tax refunds.

Q8.Should GST and QST appear as separate lines on a Quebec invoice?

Yes. Because GST goes to the CRA and QST to Revenu Québec, Quebec invoices must show the two taxes separately (or state that prices include them), along with your GST and QST registration numbers. Accounting software needs both tax codes configured in parallel on the subtotal — not QST compounded on GST.

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