The threshold question is about timing as much as amount
CRA's registration guidance shows why businesses get surprised by GST/HST. The small-supplier threshold is generally $30,000, but the date on which the business stops being a small supplier depends on whether that amount is exceeded in a single quarter or over four consecutive quarters. In some cases, the supply that crosses the line is itself taxable. That is a much sharper rule than the casual phrase 'register once you pass $30,000' suggests.
The rate on the invoice follows place of supply, not a one-rate Canada myth
CRA's rate page explains that the tax to charge depends on where the supply is considered to be made. That is why some sales are charged at 5% GST while others carry HST at the participating-province rate. The page's Nova Scotia note is especially helpful because it reminds readers that rate assumptions can go stale when provinces change their portion of the HST.
Registration belongs in the operating checklist, not as an afterthought
Once the threshold analysis says register, CRA's account-registration material turns the decision into a workflow. The business needs the GST/HST account set up correctly, the effective date captured properly, and the invoicing process aligned with the right place-of-supply rule. In other words, registration is not just a box to tick. It is the start of the collection and remittance system the business will actually live inside.
Educational content only
This guide is for general education, not personalized tax advice. Tax rules change and your facts matter — confirm anything important with a qualified professional or the cited official source before taking action.