GST QST Calculator for Canada - Quebec Sales Tax

Canadian transactions may be subject to the federal goods and services tax (GST) and, in Quebec, the Quebec sales tax (QST). The common general rates are 5% GST and 9.975% QST, producing a combined nominal rate of 14.975% when both apply. The GST and QST breakdown separates the two taxes so an invoice, receipt, or reconciliation can show each amount and the final Canadian-dollar total. Both taxes are calculated on the pretax base in the model. For a $1,000 taxable sale, GST is $50 and QST is $99.75, making the total $1,149.75. Although Quebec historically calculated QST on a base that included GST, the rate and base were changed; current ordinary calculations apply 9.975% QST directly to the price excluding GST. That is why the combined result is a straightforward 14.975% rather than a tax-on-tax calculation. To extract both taxes from an inclusive amount, divide the total by one plus the combined decimal rate. A $1,149.75 total divided by 1.14975 returns a $1,000 base. GST and QST can then be calculated separately from that base. Keep full precision until the final step because QST uses three decimal places in its percentage rate and early rounding can create cent differences. Actual obligations depend on supplier registration, place of supply, customer status, type of property or service, transaction date, exemptions, zero-rating, and special rules. Other provinces may use HST, separate provincial sales tax, or GST alone. Input tax credits and input tax refunds concern recoverability for registered businesses; they do not change the arithmetic shown on an ordinary taxable sale. Use the result to check invoices and point-of-sale totals, not to determine legal taxability or filing treatment. Confirm rates and rounding with the Canada Revenue Agency and Revenu Québec. If only one tax applies, set the other rate to zero. Tips, deposits, delivery fees, discounts, and trade-ins can have special base rules. Record GST and QST in separate liability accounts when your accounting process requires separate reporting.