Bad debts attributed to you but really owed by someone with a similar name or Social Security number will cost you big bucks if they lower your credit score. That's because a lender might charge you a higher mortgage rate -- assuming they don't reject your loan application outright. So McBride recommends starting any house hunt by pulling your credit reports and looking for errors. "You want to look for collection items showing up as unpaid even though you paid in full, bills showing up as paid late even though they weren't yours or weren't late -- things like that," he says. "Those are issues that need to be addressed." Federal law requires the three major U.S. credit bureaus -- Experian, Equifax ( EFX) and TransUnion -- to give you one free copy of your credit report each year. Some states also have separate laws that entitle you to a second free copy every 12 months. To order your free reports, go to the industry's https://www.annualcreditreport.com/cra/index.jsp site and request a copy of all three agencies' files on you. (Avoid other "free-credit-report" sites with similar Web addresses.) If you're planning to apply for a mortgage with a spouse or significant other, pull their credit reports as well. Should you uncover any mistakes (as 20% of consumers who participated in recent Federal Trade Commission study did) file a dispute with Experian, Equifax or TransUnion. Fixing problems can take weeks, so start now.