Working Backward
Once you have calculated your monthly income, multiply it by the back ratio for your particular loan. For generic purposes, it is fairly easy to work with thirty-eight. Take 38% of your monthly income or multiply it by .38. That tells you the maximum the lender wants you to spend on your housing costs and monthly consumer debt combined.
Now get out your bills and total them up to determine what you spend monthly on debt. Do not include your auto insurance or your utilities. Just creditors. For credit cards, use the minimum required monthly payment unless it is less than ten dollars. The rest should be fairly straightforward.
Deduct that amount from the total the lender wants you to spend on housing costs and consumer debt combined. Now you know the maximum the lender wants you to spend for housing costs, unless the figure is greater than 33% of your monthly income (there are exceptions, of course).
