GST and QST on a roofing quote
Two lines, never one combined tax total. That is the rule, and a word-processor template does not know it.
A roofing quote in Quebec carries two taxes: federal GST at 5% and provincial QST at 9.975%. They do not combine into a single 'tax' line. Each has its own rate, and each is calculated on the pre-tax amount.
What has to appear on the document
- The subtotal before tax.
- GST, with its rate (5%), on its own line.
- QST, with its rate (9.975%), on its own line.
- The total.
- Your GST and QST registration numbers, if you are registered.
- Your RBQ licence number.
The arithmetic, on a real example
Take a subtotal of $14,285.71 for a roof replacement. Both taxes are calculated separately on that subtotal — QST is not applied on top of GST.
| Line | Amount |
|---|---|
| Subtotal | $14,285.71 |
| GST 5% | $714.29 |
| QST 9.975% | $1,425.00 |
| Total | $16,425.00 |
A common mistake is applying QST to the subtotal plus GST. That was only true before 2013. Since then both taxes are calculated on the same base amount.
The tax follows the property, not your office
The applicable rate depends on where the building is, not where your company is registered. A quote crossing from Gatineau to Ottawa changes regime: QST no longer applies and Ontario HST does. A template with fixed rates is wrong the moment you work outside your own region.
Closlyo resolves the rate from the property's postal code across thirteen provincial and territorial jurisdictions, and prints GST and QST on two lines. Your QST number prints only if you actually hold one.
Common questions
Is QST calculated on top of GST?
No. Since 1 January 2013, QST is calculated on the pre-tax amount, the same base as GST. Both apply to the same figure.
Can I show a single combined tax amount?
No. Both taxes must be shown separately with their rates, so the customer can verify them and claim input tax credits where applicable.
Do I need to print my GST and QST numbers?
Yes, if you are registered for both. The customer needs them to claim input tax credits.
Closlyo produces the quote with both tax lines and your RBQ number, in French or English.
Updated 2026-09-22