When you put a 20% down payment on your real estate purchase, you can avoid the CMHC premium. The rule of thumb is: the larger of a down payment you make, the lower the amount of interest you will pay over the life of your mortgage. It is important to note for you to understand your financial situation and it may not be wise to stretch yourself too thin to increase your down payment and end up borrowing on credit cards or a line of credit with a higher interest rate.