Question 1

How do I calculate GST/HST on a price?

Accepted Answer

Multiply the pre-tax price by the tax rate for the customer's province, then add that to the original price. This calculator does it automatically — pick the province, enter the amount, and use the "Add tax to a price" mode.

Question 2

How do I work backward from a tax-included total?

Accepted Answer

Divide the total by (1 + tax rate) to get the pre-tax subtotal, then subtract that from the total to get the tax amount. Use the "Remove tax from a total" mode above — this is the formula it uses.

Question 3

Which province's rate should I use?

Accepted Answer

Generally, Canadian sales tax is based on where your customer is located, not where your business is based — use your customer's province, not your own.

Question 4

Does this calculator handle Quebec's QST correctly?

Accepted Answer

Yes — Quebec combines 5% GST with 9.975% QST for a combined 14.975%, calculated the same way as any other province's combined rate.

Question 5

Is BC's PST included automatically?

Accepted Answer

The calculator shows BC's combined GST+PST rate, but PST generally only applies to goods and a specific list of services, not most freelance or consulting work — see our BC invoicing guide for the details before assuming PST applies to your situation.

GST/HST Calculator

How does Canadian sales tax work?

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