Dear Liz: I am trying to help my retired parents refinance their home. Currently they are paying over 8% interest. (This loan should be illegal.) The problem is their credit score, which is around 536. They had a tax lien in 2004 (it has been paid off for over four years) and some minor credit card issues. The total card debt is less than $1,000. I see several bad footnotes on these cards. Some of the cards have a balance of less than $100. What is the best and fastest way to help them get the mortgage they deserve?

Answer: Your parents don’t have a single credit score. They each have their own scores. Mortgage lenders typically get FICO scores for each borrower from all three credit bureaus, for a total of six scores. Lenders look at the middle score for each person and typically base rates and terms on the lower of those two middle scores.

If that number is indeed 536, your parents have serious, recent credit problems. You may not think an unpaid credit card is a big deal, but it is to credit scoring formulas, which are designed to help lenders gauge a borrower’s risk of default. People with unpaid bills are far more likely to default on a new loan than people who pay their bills on time, and their respective credit scores reflect that reality. What people “deserve” isn’t a factor. How they handle their credit accounts is.

What you’re calling “bad footnotes” are likely records of late payments and perhaps charge-offs and collections activity. Those typically can’t be erased, but your parents can stop the ongoing damage to their credit by paying their bills on time and paying off any overdue bills to their credit card companies.

If the accounts have been sold to collectors, the process gets trickier. Paying off collections typically won’t help credit scores, but lenders usually want these accounts paid off before they will make a new loan. Your parents can try negotiating to have the collection accounts deleted in return for payment, but they won’t be able to erase the late payments and other negative marks reported by the original creditor.

Once they start handling their credit accounts responsibly, their credit scores will start to improve. The improvements will happen slowly, though, and they may well miss the opportunity to refinance at today’s low levels.