Generally speaking, your GDS ratio should not exceed 32% and your TDS ratio should not exceed 42%. These are however general guidelines and in practise, are not always followed. In some cases, a TDS as high as 44% is used and GDS is not even considered. These instances depend on a number of factors such as the borrower’s credit, type of mortgage, lender used and mortgage insurer. It is safe to say, however, that if your GDS and TDS fall under 32% and 42% respectively, the more likely you are to be approved for a mortgage. http://www.mortgagesbysandrine.com/mortgage-articles/what-are-gross-and-total-debt-service-ratios/