The bookstore order is ready. Mireille has the notebooks, the customer's name and two registration confirmations. Her old invoice template has one box labelled "tax."
For this ordinary taxable Quebec sale, she needs to show what she charged and make the supporting details easy to find. Before using the template, she confirms the GST and QST registration dates. A tidy invoice cannot fix a tax charged before the right account was in effect.
Calculate each tax on the selling price
For a $400 order before tax, the calculation is:
| Item | Amount |
|---|---|
| Notebooks before tax | $400.00 |
| GST at 5% | $20.00 |
| QST at 9.975% | $39.90 |
| Total due | $459.90 |
Both taxes use $400 as their base. Mireille does not calculate QST on $420 after adding GST.
A combined 14.975% calculation can produce the total tax internally, but Revenu Québec says that combined rate must not appear on the sales document. Showing separate GST and QST lines keeps this example clear. Fractions of at least half a cent round up to a cent; for several items, the taxes can be calculated on their total price before rounding. Revenu Québec's calculation rules.
Include the information the buyer needs
Mireille uses one complete template: business name, invoice date and number, buyer, description, price, both tax amounts, both registration numbers, total and payment terms. The invoice number also lets her match a later payment to this particular order.
For a registered customer's ITC or ITR documentation, Revenu Québec's minimum information bands use the total including taxes:
- Under $100: supplier name, date and total; the QST rules also require the tax amount and a description.
- $100 to $499.99: both tax amounts and the supplier's GST and QST registration numbers are required. The QST description requirement still applies.
- $500 or more: buyer identification and payment terms are also required, and the description is required under both systems.
Required information may be supported by more than one linked document. Customers can request it in writing. These bands concern supporting records, not whether a taxable sale attracts tax. Current invoice information table.
The $459.90 order falls in the middle band. Mireille still includes the buyer and payment terms because they help both people use the invoice. There is no practical benefit in removing useful details from a smaller order.
Check the transaction before copying the rates
This example assumes an ordinary taxable sale made in Quebec. An exempt or zero-rated supply, or a sale whose place-of-supply rules point to another province, needs its own treatment. Quebec's restaurant and taxi mandatory-billing requirements also need a different workflow. Collecting GST and QST.
Before sending, Mireille compares the invoice with the order: quantities, price, customer, tax treatment and total. She saves the issued copy with the order record. When the payment arrives, she can identify what was paid without rebuilding the sale from a bank deposit.
Checked October 20, 2026. For the federal documentation rules on their own, see GST/HST invoice details.
