Buying a home? Clamp down on your credit usage If you are pre-approved for a home loan, or ready to apply for a mortgage, lock down your credit use immediately. One thing you don't want to do is make significant charges on your cards. Lenders can and will check your credit report a final time before approving your mortgage. If your debt to income ratio has changed, or your credit score has dropped, you might find your mortgage declined. According to thesimpledollar.com, it is best not to apply for new credit, open new accounts, or run your cards up to the limit. A changing credit profile, especially your credit score, can cost you big money. A 100-point drop in your credit score would, at best, cause lenders to offer you a higher interest rate. A 1 percent increase on a mortgage can increase your monthly payments by $200 and increase the cost of the loan by thousands of dollars.