20% lose-it-or-lose-it yearly is my experience in Canada, and I believe that's on top of being allowed to make double payments.

And yes, the prepay penalty is generally based on the interest they would lose or a few month's interest, whichever is better for the bank at the time of payment.

But also note that if you paid the extra for a 10-year, Canadian federal law says you can prepay 100% at any time after 5 years with no penalty (or virtually no penalty?). Which is part of why longer-term mortgages are markedly more expensive.

Another interesting aspect of Canadian mortgages (as opposed to US ones) is that you can't just walk away if the mortgage is underwater (which is what a pot of people in the US did after the GFC). The bank can come after you for the difference between house value and mortgage.

That is only in states that legislate non recourse home mortgages.

https://www.loan.com/home-loans/how-non-recourse-loan-laws-v...