How do you reverse calculate HST in Ontario?

Divide the tax-included total by 1.13. A $113.00 receipt total ÷ 1.13 = $100.00 pre-tax, with $13.00 HST. For Atlantic provinces at 15% HST, divide by 1.15 instead. For Nova Scotia (14% since April 1, 2025), divide by 1.14. Always divide — never multiply the total by the HST rate.

How do I reverse calculate GST from a total?

Divide the total by 1.05. A $210.00 receipt ÷ 1.05 = $200.00 pre-tax and $10.00 GST. This works for any GST-only province or territory: Alberta, Yukon, Northwest Territories, Nunavut. In BC, Saskatchewan, and Manitoba, divide by 1 plus the combined GST + PST rate as a decimal (1.12 for BC and MB, 1.11 for SK).

How do I reverse calculate Quebec sales tax (GST + QST)?

For Quebec, divide the total by 1.14975 (the combined 5% GST + 9.975% QST). A $574.88 receipt ÷ 1.14975 = $500.00 pre-tax, with $25.00 GST and $49.88 QST. Since 2013, both GST and QST apply to the same pre-tax base, so a single divide-and-multiply gives both tax amounts.

Why is reverse sales tax not the same as multiplying by the rate?

Multiplying the tax-included total by the tax rate overstates the tax. For Ontario at 13%: $113 × 0.13 = $14.69, but the correct HST is $13.00. The error compounds — on $100,000 of tax-inclusive revenue at 13%, the wrong method overstates HST by about $1,500. The correct approach is always: pre-tax = total ÷ (1 + rate as decimal).

When do Canadian businesses use a reverse sales tax calculator?

The most common uses: separating GST/HST from receipt totals for Input Tax Credit claims, reconciling point-of-sale daily totals against book amounts, expense reporting where reimbursement is on the pre-tax cost, and verifying a supplier charged the correct tax on a tax-inclusive invoice. CRA requires registrants to track GST/HST separately for ITC purposes.

Can I reverse-calculate provincial PST separately from GST?

Yes, but you need both rates. In BC, the combined rate is 12% (5% GST + 7% PST). A $112 total ÷ 1.12 = $100 pre-tax; GST = $5, PST = $7. The same logic applies in Saskatchewan (11% combined) and Manitoba (12% combined RST). The calculator above does this automatically when you pick the province — both tax lines are shown.

Does reverse sales tax work the same for digital purchases?

Yes — the math is identical. Digital products and services follow the same place-of-supply rules as physical goods, so the customer's province determines the rate. If your Ontario-based Stripe receipt shows $90.40 total at 13% HST, divide by 1.13 to get $80.00 pre-tax. Some platforms list tax separately; when they don't, this reverse calculator gives you the breakdown.

Canada Reverse Sales Tax Calculator

Extracts GST, HST, PST, and QST from a tax-included total for any Canadian province or territory at current 2025 rates.

How This Canada Reverse Sales Tax Calculator Works

A Canada reverse sales tax calculatortakes a total price that already includes tax and works backward to find the pre-tax subtotal plus the tax amounts. This tool covers every province and territory — HST in Ontario, Atlantic Canada, and Nova Scotia; GST plus PST in British Columbia, Saskatchewan, and Manitoba; GST plus QST in Quebec; and GST-only in Alberta and the territories. Pick your province, enter the tax-included total, and the calculator breaks out GST, HST, PST, or QST as applicable.

Rates default to current 2025 values and stay editable in case your invoice uses a custom rate, a transitional rate, or a partial rebate scenario. This page locks the calculator in reverse mode — to add tax to a price instead, use our HST calculator, GST calculator, or the all-province Canada sales tax calculator.

Reverse Sales Tax Formula

The core formula is the same across all Canadian sales tax systems. Express the combined tax rate as a decimal (HST 13% → 0.13; GST+QST 14.975% → 0.14975) and divide:

Pre-tax subtotal = Total ÷ (1 + combined tax rate)
Total tax = Total − Subtotal
Each individual tax = Subtotal × that tax’s rate

Ontario worked example: $226.00 total ÷ 1.13 = $200.00 pre-tax, $26.00 HST. Quebec worked example: $574.88 ÷ 1.14975 = $500.00 pre-tax; GST = $500 × 0.05 = $25.00; QST = $500 × 0.09975 = $49.88. British Columbia worked example: $112.00 ÷ 1.12 = $100.00 pre-tax; GST = $5.00; PST = $7.00.

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Current Canadian Sales Tax Rates (2025)

Alberta, Yukon, NWT, Nunavut: 5% GST only
British Columbia: 5% GST + 7% PST = 12% combined
Saskatchewan: 5% GST + 6% PST = 11% combined
Manitoba: 5% GST + 7% RST = 12% combined
Ontario: 13% HST
Nova Scotia: 14% HST (reduced from 15% on April 1, 2025)
New Brunswick, PEI, Newfoundland and Labrador: 15% HST
Quebec: 5% GST + 9.975% QST = 14.975% combined

Why Businesses Reverse-Calculate Tax

Pre-tax separation matters for several core accounting and tax tasks:

Input Tax Credits. CRA-registered businesses claim back GST/HST paid on inputs. A reverse calc on a tax-included invoice gives the exact ITC amount.
Quick Method calculations. Small businesses using the Quick Method need the tax-inclusive total but also the pre-tax revenue for margin tracking.
Expense reporting. Many employers reimburse on pre-tax cost; the reverse calc separates the two amounts cleanly.
POS reconciliation. Daily till totals are tax-included; the GL needs the split between revenue and tax payable.
Margin checks. Selling at a tax-inclusive shelf price hides the true revenue from your cost. Reverse-calculating gives you the number to compare against COGS.

For more pricing analysis, pair this calculator with our profit percentage calculator to compute margin on pre-tax revenue, and the markup calculator for shelf-price decisions.

The Multiply-by-Rate Trap

The single most common mistake in reverse sales tax math is multiplying the total by the tax rate. The error scales with the rate — small in Alberta (5%) but large in PEI (15%):

Ontario, $113 total at 13% HST. Wrong: $113 × 0.13 = $14.69. Right: $113 ÷ 1.13 = $100 pre-tax, $13.00 HST.
PEI, $115 total at 15% HST. Wrong: $115 × 0.15 = $17.25. Right: $115 ÷ 1.15 = $100 pre-tax, $15.00 HST.
Quebec, $114.98 total at 14.975%. Wrong: $114.98 × 0.14975 = $17.22. Right: $114.98 ÷ 1.14975 = $100 pre-tax, $14.98 combined GST+QST.

Always divide by (1 + rate). Then multiply that pre-tax subtotal by each individual tax rate to get GST, HST, PST, or QST separately.

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Place-of-Supply: Which Rate to Reverse

For Canadian transactions, the tax rate is set by the customer’s province under CRA place-of-supply rules. If your receipt is from an Ontario business selling to a customer in Manitoba, the tax on the receipt is 12% Manitoba GST+RST, not 13% Ontario HST. When reverse-calculating, always use the rate that was actually charged — check the invoice or receipt for the tax line, or look up the seller’s shipping address rules.

Digital goods, real property, and some services have specific place-of-supply rules. For most B2C transactions, the customer’s billing or shipping address dictates the rate. For B2B transactions, the customer’s usual place of business applies. CRA and Revenu Québec publish detailed guidance for borderline cases.

Disclaimer

This calculator is for informational purposes only. Tax rates change; always verify the rate on your specific transaction with the Canada Revenue Agency, Revenu Québec, or your provincial finance ministry before relying on it for a tax filing, ITC claim, or contract. Consult a Canadian tax professional for advice specific to your business situation.

Sources & References

GST/HST rates by province — Canada Revenue Agency
Input tax credits — recover GST/HST paid — Canada Revenue Agency
GST and QST — Businesses — Revenu Québec