A mortgage is a contract. Banks usually tie your mortgage payments to a pool of money based on Bonds or some form of guaranteed investment certificates. If you want out of your mortgage term contract in Canada (before it expires) in order to pay a lower interest rate someone else has to get a lower interest rate on their money. In simple terms if you win someone must lose. The only fair method for all concerned is for you to pay the bank an Interest Rate Differential (IRD) to exit your mortgage.
If a Bank calculates the correct IRD they receive an equivalent amount of interest now instead of later. The IRD is based upon present value future value calculations that have been around since Fibonacci developed the algebraic equation in 1202 AD(in his famous Book of Calculations). Personal computers today are household items and my amortization.com software has been available since 1984, enabling one to calculate the IRD. It’s ironic that even in March of 2000 some Canadian Banks were still reluctant to provide a borrower an IRD calculation. Instead the Canadian Bankers Association released a 13 page booklet that gave a tedious procedure to calculate an approximate IRD. If you wanted the accurate IRD algebraic equation you have to request it.