Too many borrowers may be unfairly blaming credit scores for their higher-than-expected loan rates or extra credit-card fees, according to a recent working paper.

The real culprit may be your own misunderstanding of how the lending process works, coupled with a failure to conduct adequate research before you apply, suggests the MIT Department of Economics working paper.

The paper, written by a team of Federal Reserve and university researchers led by Sumit Agarwal of the Federal Reserve Bank of Chicago, admits a FICO credit score may determine if you're offered a loan. But other factors may contribute more heavily to your rate and fees.
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Take a home-equity loan or home-equity credit line: The greatest impact on your annual percentage rate is based on the "loan-to-value ratio," the report said. That's the percentage of the home's appraised value that you're actually borrowing.

Lenders often issue tiered annual percentage rates, based on loan-to-value ratios of 80% or less, 80% to 90% and 90% or more. So if you're shopping lenders, expect any rate you're quoted to be based on your home's loan-to-value ratio.

Too often, the paper indicates, potential borrowers misestimate their home value and find themselves asking lenders the rates for the wrong loan-to-value category. Meanwhile, once you apply for a loan at the higher rate you're quoted, loan officers often have discretion to give it to you -- despite the fact that they typically have access to appraisal information that could place you in the correct loan-to-value ratio category at a lower rate.

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