Canada's record pace of interest rate hikes has led to the repayment period for many variable rate mortgages lengthening to over 30 years, helping to shield households from higher borrowing costs but raising debt loads and worrying regulators. Variable rate mortgages in Canada typically require borrowers to make regular payments in fixed amounts. Negative amortization is a situation in which borrowers are adding to the principal and occurs when interest rates climb as high as the trigger rate.