Reverse Sales Tax Calculator
You have an amount that already includes tax (an invoice total, a receipt, a sticker price) and want to know what goes to the seller and what goes to the government. This calculator runs the usual calculator in reverse: instead of adding tax to a price, it strips tax out of a total. Enter the tax-included amount, choose your province, and the price before tax appears along with the GST and QST breakdown.
Reverse Sales Tax Calculator
The total amount, tax included.
Calculation receipt
GST and QST calculated separately on the amount before tax.
Example: an Item at $114.98 Tax Included in Quebec
An item listed at $114.98 in Quebec, tax included, corresponds to a base price of $100.00: GST accounts for $5.00 and QST for $9.98, for $14.98 in tax total. The merchant keeps $100.00; the remaining $14.98 is remitted to the tax authorities.
The calculation comes down to one division. In Quebec, both taxes apply separately to the price before tax (QST hasn't been calculated on top of GST since 2013), giving a combined rate of 14.975%:
- Price before tax: $114.98 ÷ 1.14975 = $100.00
- GST: $100.00 × 5% = $5.00
- QST: $100.00 × 9.975% = $9.98
- Check: $100.00 + $5.00 + $9.98 = $114.98
The divisor changes by province: 1.13 in Ontario, 1.14 in Nova Scotia, 1.15 in New Brunswick, 1.12 in British Columbia and Manitoba, 1.11 in Saskatchewan, 1.05 in Alberta and the three territories. The calculator above applies the correct rate automatically: see the full rate table by province.
Before-Tax Calculation: Recovering the Net Price from a Total
A before-tax calculation starts from the amount actually paid and works back to the net price, the one on the shelf before the register added tax. The operation is a division, not a subtraction: removing 14.975% from a total doesn't give back the starting price.
To calculate the amount before tax, divide the total by 1 plus your province's combined rate. In Quebec, that's total ÷ 1.14975; in Ontario, total ÷ 1.13. On a $229.95 receipt in Quebec, the price before tax is therefore $229.95 ÷ 1.14975 = $200.00.
The common mistake. Subtracting 14.975% from $229.95 gives $195.51, which is $4.49 less than the real price before tax. The percentage applies to the net price, not the total, which is why you need to divide.
When to Use a Reverse Sales Tax Calculation
- A self-employed worker who needs to separate the GST and QST collected from a tax-included amount for their tax return.
- An expense report or invoice showing only the total, when bookkeeping requires the amount before tax.
- Comparing a tax-included price display against a before-tax display.
- Budgeting: knowing how much of an expense actually goes to tax.
The sales tax guide details how GST, QST, HST and PST work, and which goods are zero-rated or exempt.
Frequently Asked Questions About Reverse Sales Tax
What is a reverse sales tax calculation?
It's the opposite of the usual calculation: instead of starting from a price before tax to find the total, you start from a tax-included total to recover the starting price and the exact amount of each tax. It's also called a reverse tax calculator or tax-included calculator, but it's always the same operation.
What is the formula to remove tax from an amount?
Divide the total amount by 1 plus the province's combined rate, expressed as a decimal. In Quebec, that's total ÷ 1.14975. Subtracting the percentage directly from the total is the most common mistake: it gives too low a result, because the rate applies to the price before tax, not to the total.
Is QST calculated before or after GST when working backwards?
Neither: both are calculated independently on the same recovered price before tax, exactly as in the forward direction. On a $114.98 total in Quebec, the price before tax is $100.00, GST is $5.00 (5% of $100.00), and QST is $9.98 (9.975% of $100.00): neither tax is calculated on the other.
Is there a free reverse sales tax calculator for every province?
Yes, this page has one. It covers all thirteen Canadian provinces and territories, not just Quebec: select the province, enter the tax-included amount, and each tax is broken out separately.
Before You Use the Result
The amounts shown are an estimate provided for informational purposes. A tax-included total may contain non-taxable items (tip, deposit, zero-rated fees, basic groceries), in which case a reverse calculation applied to the whole amount overstates the tax. Check your invoice's detail if in doubt.
The rates used come from the Canada Revenue Agency and Revenu Québec. Our verification method is described on the About page; the full reverse calculation formula is detailed in the guide.
CalculatriceTaxes.ca is an independent site. It is not affiliated with the Canada Revenue Agency, Revenu Québec, or any provincial government.