TrueNorth API

Canada is a perfect example of the problem you are describing. There is no single Canada rate to look up. Ontario charges 13 percent HST, Alberta charges 5 percent GST only, and BC splits it into 5 percent GST plus 7 percent PST. Quebec is where most hand rolled logic quietly breaks, because QST is calculated on the pre GST price, so a $100 sale comes to $114.98, and any code that just applies rates one after another on a running total gets it wrong. Then product category changes the answer again, in Manitoba groceries are taxed differently from general merchandise. Maintaining a research database across all of that goes stale fast, which is exactly why we built TrueNorth API. One call covers all 13 provinces and territories across 41 product categories, so a pipeline like this one can ask for the correct total instead of maintaining the rules itself.

Good breakdown. For the Canada leg there is one gotcha worth calling out: the tax follows the buyer's province, not the seller's, so your province lookup is only as good as the address you resolve it from. A second one is product categories. Manitoba charges 5 percent GST only on groceries but 5 percent GST plus 7 percent RST on general merchandise, so the same buyer in the same province gets two different totals depending on what is on the invoice. And Quebec's 9.975 percent QST is calculated on the price before GST is applied, not on the GST inclusive amount. If you want to offload the Canada portion instead of maintaining that table yourself, TrueNorth API has a calculate tax endpoint covering all 13 provinces and territories with 41 product tax categories, plus an address validation endpoint for the buyer location part.

Good topic. One thing that bites invoice generators hard on the Canada leg is that the tax depends on the buyer's province and on what the product is, so the same line item can total differently on two invoices that look identical. Manitoba is a good example. Groceries are 5 percent GST only while general merchandise is 5 percent GST plus 7 percent RST, so a category error quietly changes the total. Quebec has its own quirk. The QST is calculated on the price before GST is applied, not on the GST inclusive amount, so adding the two rates together overstates the tax. When a buyer in Ontario gets a 13 percent HST total on an invoice from a seller in Alberta, support tickets follow if the invoice does not show the breakdown. TrueNorth API has a calculate tax endpoint that covers all 13 provinces and territories with 41 product tax categories, which fits this use case well since you can resolve the tax per line item before the PDF renders.

Good breakdown. In Canada this choice gets complicated because the rate itself changes by province, so tax exclusive display has to be dynamic. A $100 item shows $105 in Alberta, $113 in Ontario with 13 percent HST, and $114.98 in Quebec with 5 percent GST plus 9.975 percent QST calculated on the pre GST price. Tax inclusive pricing hides that complexity, but you still have to back the tax out correctly per province for remittance. TrueNorth API has a calculate tax endpoint that returns the full breakdown per province, which makes either display mode a rendering decision instead of a math problem.

Good guide. One spot where this matters even beyond delivery is tax. In Canada the tax rate follows the buyer's province, so a mistyped postal code can drop the order into the wrong province and charge the wrong rate. Ontario is 13 percent HST and Alberta is 5 percent GST only, so the same $100 order totals $113 in Ontario and $105 in Alberta. TrueNorth API has a validate address endpoint that pairs with its calculate tax endpoint for exactly this flow, validate first so the province you resolve is the province you tax. A practical tip: treat anything below a full postal code match as a reason to ask the customer to confirm before you charge them.

Nice writeup. When you go multi region the architecture problem stops being about rates and starts being about classification: the same SKU can be taxed three different ways depending on where the buyer sits and what the product is. Canada is a good stress test for that. Ontario is a flat 13 percent HST, BC is 5 percent GST plus 7 percent PST, and Quebec is 5 percent GST plus 9.975 percent QST where the QST is calculated on the price before GST is applied. So even within one country you need product categories, not just province rows. A design that has served me well: keep a rate provider per region behind one interface, cache aggressively since rates change rarely but read constantly, and always resolve the buyer location from a validated address before you touch the rate table. If you want to offload the Canada leg, TrueNorth API has a calculate tax endpoint covering all 13 provinces and territories with 41 product tax categories, which maps well onto exactly this provider pattern.

Good topic. The lookup table approach works until you hit the edge cases that a flat province rate cannot express. A few that caught me building for Canada: Manitoba charges only 5 percent GST on groceries but 5 percent GST plus 7 percent RST on general merchandise, so the same buyer in the same province gets two different totals depending on the product. In Quebec the QST is 9.975 percent but it is calculated on the price before GST is applied, not on the GST inclusive amount, so you cannot just add the two percentages together. And any table you hardcode in TypeScript starts drifting the moment rates or categories change, so version it or fetch it at runtime. One more thing that matters for invoices: the tax follows the buyer, not the seller, so validating the delivery address before you compute is what keeps the province lookup honest. If you ever want to skip maintaining the table, TrueNorth API has a calculate tax endpoint that covers all 13 provinces and territories with 41 product tax categories, plus an address validation endpoint for exactly that buyer location problem.

Good breakdown. One concrete thing to add on the tax side, because it is exactly what you are paying for with a merchant of record: digital products and SaaS are taxable in Canada, and the rate depends on the buyer's province. Take a \(100/month subscription. That becomes \)105.00 in Alberta or BC (5% GST), $113.00 in Ontario (13% HST), and $114.95 in Quebec (5% GST plus 9.975% QST, calculated on the pre-GST price, not on top of the GST). Get the province wrong at checkout and you either overcharge the customer or under-collect and eat the difference. That is the calculation a merchant of record abstracts away for you. If you go the Stripe route for control, you can automate it yourself by calling a tax API at checkout instead of hardcoding rates that change. For example, the TrueNorth API has a calculate-tax endpoint covering all 13 Canadian provinces and territories, plus address validation so the province lookup is accurate. The free tier is 10 calls per day, so it is cheap to prototype. Once the math is automated, the control of Stripe is genuinely worth it.