Canada Reverse Sales Tax (GST/HST/PST) Calculator

How the Reverse Sales Tax Formula Works

A reverse sales tax calculation recovers the original pre-tax price from a total that already includes tax. The formula is:

$$\text{Pre-tax price} = \frac{\text{After-tax total}}{1 + r}$$

where $r$ is the total sales tax rate as a decimal. Subtracting the tax from the total at the same rate doesn’t work: tax is a percentage of the pre-tax price, not of the total, so taking 13% off a total understates the price.

Step-by-Step Example: Ontario (13% HST)

Suppose a receipt shows a total of $226.00 in Ontario:

Worked examples at different provincial tax rates

Splitting a receipt with two taxes

In British Columbia, Saskatchewan, Manitoba and Quebec, a receipt shows the GST and the provincial tax as separate lines. If you only have the total, find the pre-tax price with the combined rate first, then apply each rate to that price. Where a provincial sales tax is charged, the GST is calculated on the price without it.

A $112.00 total in British Columbia works out like this:

• Pre-tax price: $112.00 ÷ 1.12 = $100.00
• GST (5%): $5.00
• PST (7%): $7.00

How this reverse sales tax calculator works

1. Enter the after-tax total: the amount shown on your receipt or invoice.
2. Select the province: this sets which rates apply.
3. View the breakdown: the pre-tax price and each tax component.

If you want to add sales tax to a pre-tax price instead, use the sales tax calculator.

Why you might need a reverse sales tax calculator

Business expense tracking

When recording business expenses, you often need the tax component of a receipt total. If you are registered for the GST/HST, you can generally recover the GST/HST you paid or owe on purchases for your commercial activities as input tax credits (ITCs), provided you have the documents to support the claim and claim it within the time limit; purchases for personal use or for making exempt supplies don't qualify. ITCs reduce the GST/HST your business remits; the GST/HST calculator for business owners shows how they affect what you owe. In a province with two taxes, only the GST line counts toward a GST input tax credit, which is why splitting the two taxes matters (in Quebec, businesses registered for the QST recover the QST line separately, through input tax refunds claimed from Revenu Québec).

Receipt analysis and budgeting

Credit card and bank statements show the total charged, not the pre-tax price. A reverse calculation shows how much of each purchase went to tax.

Cross-province price comparisons

Removing the tax gives the true pre-tax price, so you can compare prices between provinces with different rates, which matters most for large purchases such as a vehicle.

Splitting shared expenses

When dividing a shared purchase, the pre-tax price lets you split costs fairly, especially if some items were zero-rated or exempt and others were taxed. The sales tax by province page lists what isn’t taxed; a receipt mixing taxed and untaxed items needs the untaxed items removed before you reverse the rest.

Related calculators

• Sales Tax Calculator: calculate tax on a pre-tax amount by province
• GST/HST Calculator for Business Owners: estimate GST/HST remittance and input tax credits
• Income Tax Calculator: estimate federal and provincial income tax
• Land Transfer Tax Calculator: estimate property purchase taxes
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