# Quebec sales tax on customer invoices

> Review qualifying sales and registration before adding QST to a Quebec invoice.

Source: https://app.getoatmilk.com/docs/quebec-sales-tax

Quebec sales tax (QST) depends on the seller's registration and the sale. A Quebec address alone does not establish that the seller must collect QST. Oatmilk reviews the company's saved setup and the records behind the calculation before issuing a Quebec invoice.

## Review the company's setup

Open a Quebec invoice and review its QST calculation. Confirm where the company operates, whether it is already registered under the general or specified QST system, and whether the available sales history is complete. A registered company needs its registration evidence and effective date. A platform confirmation does not register the company with Revenu Québec or cancel an existing registration.

This automatic flow covers ordinary services under the general place-of-supply rules. Goods, property, events, transport, sales handled by a collecting distribution platform and other special supplies need their applicable rules reviewed separately. A customer address cannot settle every supply category.

For an eligible supplier outside Quebec that is registered for GST/HST, the specified-system registration test is **more than C$30,000** of qualifying taxable Quebec supplies to specified Quebec consumers over a 12-month period. Exactly C$30,000 does not cross this threshold. Zero-rated and exempt sales do not count. A customer can be a business and still be a specified Quebec consumer; satisfactory proof of general QST registration changes the specified-system treatment. [Revenu Québec registration rules](https://www.revenuquebec.ca/en/businesses/consumption-taxes/gsthst-and-qst/special-cases-gsthst-and-qst/suppliers-outside-quebec/qst-registration-for-suppliers-outside-quebec/registration-under-the-specified-system-suppliers-outside-quebec-who-are-registered-under-the-general-gsthst-system/).

The review shows the rolling period, source invoices, proposed invoice, qualifying Canadian-dollar amounts, known expected sales and any gaps. Consider reasonably expected supplies as well as past invoices. Sales recorded elsewhere need supporting Canadian-dollar amounts. Missing currency conversion, incomplete records and unresolved company facts remain visible. Payments of an invoice are not another sale. Drafts are proposed amounts, not issued revenue.

Undated expected sales are assessed as of today. If their missing dates could change a future 12-month result, enter dated expected sales before confirming. Backdating or future-dating the proposed invoice does not move a current forecast away from the current sales history.

The statutory test covers any relevant 12-month period and can include reasonably expected consideration. Foreign amounts require a fair, reasonable and consistent Canadian-dollar conversion. An estimated future amount is a planning input, not verified revenue. [QST Act, sections 477.4.3–477.5](https://www.legisquebec.gouv.qc.ca/en/document/cs/T-0.1).

Companies carrying on business in Quebec, already registered generally, or subject to special mandatory-registration rules need the general rules reviewed. Their obligations cannot be decided using only this Quebec-consumer sales threshold. [General registration rules](https://www.revenuquebec.ca/en/businesses/consumption-taxes/gsthst-and-qst/registering-for-the-gst-and-qst/).

## Confirm once and keep checking

An administrator confirms the current calculation and facts. Oatmilk saves that setup for later invoices and rechecks each invoice before issuance. Crossing the threshold, changed registration facts or unresolved evidence can require another review. A known earlier threshold breach remains relevant after its sales age out of the current period. Falling below the threshold does not automatically cancel registration.

General and specified QST registrations have different customer rules. A customer's general QST registration can remove collection under the specified system; it does not remove collection under the general system. QST is calculated separately from GST on the pre-tax price. [Collection rules](https://www.revenuquebec.ca/en/businesses/consumption-taxes/gsthst-and-qst/special-cases-gsthst-and-qst/suppliers-outside-quebec/collecting-the-qst/), [tax calculation](https://www.revenuquebec.ca/en/businesses/consumption-taxes/gsthst-and-qst/collecting-gst-and-qst/calculating-the-taxes/).

## API, MCP and terminal

`invoices.qstReview` reads a saved invoice or proposed draft. `invoices.qstConfirm` saves an administrator's explicit confirmation using the returned review hash and settings revision. A changed calculation requires another review. Read the generated action reference for current fields and validation.

Ask AI, connected MCP clients and the terminal use these same server actions and issuance checks. Card-capable clients can open the QST review in place. Plain-text clients receive the calculation and source records. The compliance library keeps cited guidance, and the compliance researcher watches official sources for relevant changes. Guidance describes the rules; only the invoice review checks the company's invoice records.