If you have more than 20 percent of the cost of a home saved up for a downpayment, it’s probably a good idea to go right ahead and buy that property — come January 1, 2018, it will be much harder to qualify for a mortgage. The Office of the Superintendent of Financial Institutions (OSFI), Canada’s banking regulator, confirmed on Tuesday, Oct 17 that there will now be a qualifying “stress test” for all uninsured mortgages, affecting consumers with down-payments of 20 percent or more. Under current housing rules, only borrowers with a down-payment of less than 20 percent require mortgage insurance.…