Mortgage amortization periods will be reduced from 35 years to 30 years for CMHC insured mortgages. The maximum amount canadians can borrow to refinance their mortgages will be lowered from 85 per cent to 80 per cent the value of the home. CMHC will not cover mortgages over $1 million-which means buyers will need 20 per cent downpayment to get an uninsured mortgage. These changes take effect July 9, 2012.