The Globe and Mail reports in its Friday edition that new parents looking to buy a home or renew their mortgage need to be prepared. Guest columnist Penelope Graham writes that taking parental leave -- 18 months is the maximum for combined maternity and parental leave in Canada -- lowers your income. Even though it's temporary, it can drastically reduce the amount of mortgage you qualify for. The key to preventing this is to get a return-to-work letter from your employer that definitively states the date you'll be back at work and the salary you'll be earning. With this in hand -- along with a T4 or end-of-year paystub -- your lender shouldn't have an issue using 100 per cent of your income in your mortgage qualification. If you are taking a 12-month parental leave, this is usually pretty cut-and-dry, but if you are taking more than 12 months, problems can arise. Lender requirements vary. At BMO, income is assessed using the "lesser of the most recent year's income or a two-year average, supported by documentation such as T4s, personal tax returns, and notices of assessment." RBC, meanwhile, stated that, "Any requests of this nature would be assessed case by case and dependent on strength of overall application."