Mortgage payments aren't the only expense to consider when evaluating whether you can afford to buy a house and how much you can afford to spend. There are also property taxes, which can be substantial, homeowner's insurance, repairs and maintenance, utilities, sewer and water bills, major appliances, landscaping and yard maintenance costs, and more. Utilities can be very expensive if you live in a cold region of the country such as the Northeast, where bone-chilling winters drive up heating costs, or in the South, where hot, humid summers run up air-conditioning bills.

If you've been renting and are considering buying a house, try to think of all the things you'll need to buy that you didn't need when you had a landlord who took care of repairs and yard work. You may need a lawnmower, weed whacker, chipper/shredder, leaf blower, rototiller, or other lawn and garden equipment; a washer and dryer, a new stove or refrigerator, or other household appliances; a snow blower or snow plow. Then there are the items that aren't absolutely necessary but that you'll want to have as soon as possible, such as window coverings (blinds, shades, or curtains), and new or additional furniture. If you're buying a fixer-upper, you'll need money for materials even if you intend to do most of the work yourself. Even a few of these things can add up to a lot of expenses.

Most people use all the cash they can scrape together for the down payment and closing costs, and then end up having to use credit to buy the things they need or want for the new house. Between the mortgage payments and the increased credit card payments, you may struggle to make ends meet. If you plan ahead and know how much house you can really afford, you can avoid being house poor — unable to afford anything but the house payment. Being house poor can propel you more deeply into debt because you use credit for purchases you'd pay cash for if you weren't so strapped.