Reverse Sales Tax Calculator (Canada)

What the reverse sales tax calculator does

Sometimes you have the total, not the base: a receipt shows one tax-inclusive figure, a supplier quotes an all-in price, or a till total lands in your books. Enter the tax-inclusive amount and the province, and the calculator recovers the pre-tax base and the sales tax built into the price, for any province or territory.

Why removing tax is not just subtracting a percentage

Adding tax takes a percentage of the smaller base price. Subtracting the same percentage from the larger total removes too much. The correct method divides the total by one plus the rate, which recovers the exact base, and the tax is the total minus the base. The base and tax always add back to the total you entered.

The rate is used as a decimal: for Ontario’s 13% you divide by 1.13, for Quebec’s 14.975% by 1.14975.

The rates it applies

• 5%: Alberta, Northwest Territories, Nunavut, Yukon (GST only).
• 11%: Saskatchewan.
• 12%: British Columbia, Manitoba.
• 13%: Ontario.
• 14%: Nova Scotia, after its 2025 reduction.
• 14.975%: Quebec.
• 15%: New Brunswick, Newfoundland and Labrador, Prince Edward Island.

Worked examples

An Ontario receipt shows $113.00 with tax. Dividing by 1.13 gives a base of $100.00, so $13.00 is HST. Subtracting 13% of $113.00, $14.69, would have overstated the tax.

The same $113.00 in British Columbia, at 12%, contains a base of about $100.89 and about $12.11 of tax. In Alberta, at 5%, it contains about $107.62 and $5.38 of GST. A Quebec total of $114.98 divided by 1.14975 returns a base of about $100.00 and $14.98 of GST and QST. The same-looking total hides a different base and tax in each province, which is why you choose the jurisdiction.

How the reversal differs across the country

In the HST provinces you divide by one plus the single HST rate; in British Columbia, Manitoba and Saskatchewan by one plus the combined GST and PST; in Quebec, where GST and QST both apply to the same pre-tax base, one division by 1.14975 recovers it; and in Alberta and the territories the divisor is 1.05. The calculator holds all of them.

When to use it

• Backing the tax out of a receipt for bookkeeping or an expense claim.
• Finding the pre-tax figure to record revenue or costs.
• Checking that a tax-inclusive quote matches the pre-tax price you expected.
• Separating the tax in a mixed or rounded total.

Registrants claiming input tax credits need to separate the GST or HST paid from the purchase price, which is this step. Record the province and rate you used with each entry.

Common mistakes to avoid

• Subtracting the rate instead of dividing, which overstates the tax.
• Choosing the wrong province, which silently applies the wrong divisor.
• Reversing a receipt that mixes taxable items with exempt or zero-rated ones such as basic groceries; one reversal cannot recover the true split.

Assumptions and limits

The calculator assumes the whole total was taxed at the single combined rate for the province you choose and that the item is fully taxable. Receipts that mix taxable and exempt items, include point-of-sale rebates or round oddly give an estimate rather than an exact reconstruction. Confirm the current rate and the taxability of the specific supply with the relevant tax authority before relying on the result for a filing.

This is general information, not financial advice.

About This Reverse Sales Tax Calculator

Use this reverse sales tax calculator to get an instant, accurate estimate. The figures follow official CRA guidance and every rate and threshold is kept up to date for 2026. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.