Your debt-to-income ratio (DTI) is the percentage of your gross monthly income set aside for paying debts. While some loans may qualify you for up to 50 percent of your monthly gross income, it’s advisable that you use no more than 30 percent. this is called the “back-end” ratio. If, for example, you have a $5,000 gross monthly income, Adamaitis gives this scenario: After taxes, you might actually clear around $3,600. If you expect to owe 30 percent of your gross monthly income, that’s $1500 a month, leaving you a grand total of $2,100 to live on. At this rate, your 30 percent debt is actually cutting into 42 percent of your monthly income, after taxes. (AOL Real estate 6/25/11).