About This Sales Tax Calculator
Use the sales tax calculator to see how one or two tax rates change a price. Enter an amount, then add a single rate or a pair of rates — for example a federal and a provincial tax. When a region stacks taxes, turn on "Tax 2 on top of Tax 1" so the second tax is calculated on the amount already including the first, the way Quebec applies GST and QST. Ecommerce tax rules can still depend on customer location, product category, marketplace collection, exemptions, nexus, and local rules, so this tool is for arithmetic and planning rather than compliance decisions.
How to Use the Calculator
- Enter the taxable amount you want to test.
- Add a single tax rate, or two rates — name each one (e.g. GST and QST).
- If the second tax should apply on top of the first, turn on "Tax 2 on top of Tax 1".
- Review each tax amount and the total with tax.
- Confirm the rates and tax rules with your marketplace, tax software, or professional advisor.
How the Math Works
With one tax: tax amount = taxable price × rate, and total = taxable price + tax. With two taxes in parallel: each tax is calculated on the same taxable price, then added together. With stacked taxes (Tax 2 on top of Tax 1): Tax 1 is calculated on the taxable price, then Tax 2 is calculated on the taxable price plus Tax 1 — this is how Quebec applies QST on top of GST. Either way, total = taxable price + tax 1 + tax 2.
Calculator results are estimates, not official platform statements. Marketplace fees, processor rates, carrier charges, taxes, return costs, and discounts can change by category, region, seller account, customer location, and timing. Use the result as a planning checkpoint, then confirm important assumptions with your marketplace dashboard, accounting records, shipping software, or a qualified professional.
Interpretation Tips
- Use two rates when your region has both a federal and a provincial tax, and turn on "Tax 2 on top of Tax 1" when the second tax is charged on the first — like Quebec GST + QST.
- Some regions apply multiple taxes in parallel (each on the base price) instead of stacking them — the toggle covers both.
- Marketplaces may collect and remit tax in some jurisdictions, but sellers still need records.
- Do not guess taxability for official filings.
- Different products can have different tax treatment.
- Use tax software or professional guidance for multi-state or cross-border sales.
Sales Tax Calculator FAQ
Can this tell me which tax rate to use?
No. You must provide the rate and confirm tax rules separately.
How do I calculate two taxes at once?
Enter both rates in the Tax 1 and Tax 2 fields, and name each one (for example GST and QST). The calculator shows each tax amount separately and the total with both taxes.
What does "Tax 2 on top of Tax 1" mean?
Some regions charge the second tax on the amount that already includes the first tax, instead of on the base price alone. Quebec is a common example: QST is calculated on the GST-inclusive price. Turn the toggle on to stack taxes that way, or leave it off to apply both taxes to the base price.
Do marketplaces handle sales tax?
Some marketplaces collect tax in certain places, but rules vary. Keep records and verify obligations.
Is this tax advice?
No. It is only a math estimator. Consult a qualified tax professional for compliance.