Dear Liz: We’re planning to refinance our mortgage and are concerned about generating multiple credit inquiries which would lower our excellent credit scores. Is there some kind of licensed, bonded ethical middle-agent who could get just one official credit report from each of the three bureaus and then send it to all the lenders I designate? Our FICOs are so good that we want lenders to compete for our refi business but don’t want the process itself to lower FICOs just for inquiries only.

Answer: The FICO formula has you covered. With the FICO scores most lenders use, multiple mortgage inquiries made within a 45-day window are aggregated together and counted as one. Furthermore, any inquiries made within the previous 30 days are ignored entirely. That allows you to rate shop for mortgages without dramatically affecting your scores.

The FICO formula extends this “de-duplication” process to two other types of borrowing: auto loans and student loans. Only similar types of inquiries are grouped together, however. If you shopped for both mortgages and auto loans, then two inquiries eventually would be factored into your credit scores, rather than just one.

Credit cards, personal loans and other types of borrowing don’t get the same treatment. If you apply for two credit cards while shopping for a mortgage, you would have three inquiries — two that are immediately factored into your scores and a third that would be counted after 30 days had passed.

Also, some lenders use older versions of the FICO formula that have a shorter rate-shopping window — 14 days instead of 45. If you want to be absolutely sure your mortgage shopping has a minimal impact on your scores, you can limit your shopping to that two-week period.