When you apply for the mortgage, the lender looks at your credit report and your credit score. Then, the day before or day of closing, the lender looks at your credit again. If there’s a substantial change — say you maxed out your credit cards to buy furniture and appliances, or you got a loan to buy a car — the lender might have to delay, or possibly cancel your mortgage closing.
So our advice is to keep your finances steady between the time you apply for a mortgage and the time you close on it. Don’t charge up your credit cards and don’t apply for new credit while the mortgage is going through the underwriting process.