Free · forward + reverse · private

Québec GST/QST calculator: add or remove sales tax.

Calculate 5% GST and 9.975% QST from a before-tax amount, or work backward from a tax-included total. The calculation stays in your browser and keeps each tax line visible.

Two tax lines. One reconciled total.

Enter an amount to see the subtotal, GST, QST, total tax, and final total.

Current Québec method

Both taxes use the price before GST.

Revenu Québec’s current rules calculate GST and QST on the same sale price. The tool uses separate tax lines and rounds each to the nearest cent.

100.00

Start with a before-tax subtotal

On C$100.00, GST is C$5.00 and QST is C$9.98 after cent rounding.

114.98

Add both rounded tax lines

The example total is C$114.98. QST is not compounded on the C$5.00 GST.

÷1.14975

Reverse a tax-included total

The reverse mode estimates the subtotal, then reconciles the displayed tax lines to the exact total entered.

Use the result within its scope

The math is fixed; tax treatment is not.

This calculator assumes the transaction is in Canadian dollars and fully taxable by both 5% GST and 9.975% QST. It does not decide registration, place of supply, exemption, zero-rating, or whether a special rule applies. Revenu Québec also permits one-step register calculations, so invoice-level rounding can differ.

Revenu QuébecBasic GST/QST rules and current ratesOpen the official source Revenu QuébecTwo-step, one-step, and cent roundingOpen the official source Canada Revenue AgencyGST/HST calculator and provincial rate tableOpen the official source

Questions behind the calculation

Four details worth checking before you use the result.

Is QST calculated on top of GST?

No under the current general method. GST is 5% of the sale price and QST is 9.975% of the sale price excluding GST, so both use the same before-tax base.

What is the combined GST and QST rate in Québec?

When both taxes fully apply, the arithmetic combined rate is 14.975%, producing a factor of 1.14975 before rounding. Revenu Québec says the combined rate must not appear as a tax rate on the document attesting the sale.

Why can a reverse calculation differ by a cent?

Registers and invoices may round each item, each tax line, or the total at different stages. The CRA cautions that reverse estimates can differ from final totals by one or two cents.

Does this tool decide whether GST or QST applies?

No. Taxability, registration, place of supply, zero-rating, exemptions, and special sectors depend on facts outside this calculator.

From tax math to invoice evidence

Keep the tax lines with the required invoice fields.

Compare this Québec result with every Canadian jurisdiction, then use the free invoice requirements checker for the current CRA and Revenu Québec supporting-information bands. The C$19 Action Kit adds the classification and evidence questions that a calculator cannot answer.

Compare all Canadian jurisdictions Estimate a Québec Quick Method remittance Check invoice requirements See the C$19 Action Kit