Canada: the province sets the rate, and the trade-in comes off first
Canada is one of only two countries here where the tax is both added on top of the advertised price and reduced by a trade-in, which is why the Canadian page keeps the tax field and the American one does too while most of Europe has neither.
The rate is not national. Combined federal and provincial sales tax on a car runs from 5% in Alberta, where only GST applies, to 15% in most of Atlantic Canada, so the 12% the page opens on is a mid-range starting figure rather than a rate that applies anywhere in particular. Set it to your own province before reading the payment: on a $45,000 car the gap between Alberta and Newfoundland and Labrador is $4,500 of tax, financed at your loan rate for the whole term. Nova Scotia cut its HST to 14% in April 2025, which is a reminder that the number is worth checking rather than remembering.
Most provinces charge the tax after the trade-in is deducted, though the treatment of the federal portion varies. The calculator follows the majority rule, so a part-exchange lowers the tax as well as the amount financed.
One local habit is worth flagging. The usual new-car term quoted by Canadian dealers is 72 months, which sits exactly at the point where this calculator starts warning about long loans: 72 is not flagged, 84 is. That warning is about depreciation outrunning repayment, and it applies to a six-year loan almost as much as a seven-year one.