My loan officer said something almost in passing, the kind of line you'd miss if you were checking your phone. "Your FICO came in a little lower than I'd like. Let me run the other score too." I didn't even know there was another score. I'd spent years assuming a mortgage rate came from one number, pulled from one bureau, and that was that.

Turns out that's not how it works anymore, at least not for loans backed by Fannie Mae or Freddie Mac. Lenders can now check borrowers against two different credit scoring models, classic FICO and VantageScore, and in a lot of cases they're allowed to use whichever one comes back higher. My VantageScore, the kind of score Credit Karma shows you for free, was 31 points above my FICO. I have no idea why. Same bills, same payment history, same me. The two companies just weigh things differently, and apparently that gap is common enough that it's reshaping how rates get set.

I refinanced in July, mostly because my adjustable rate was about to reset and the thought of it kept me up more than I'd like to admit. I'd braced for a number in the low 7s based on what I was seeing online. What I got instead landed closer to 6.6%, and the loan officer credited part of that gap to the second score pull. I'm not going to pretend I fully understand the math behind why a 31-point swing moved my rate as much as it did. I just know my payment is $94 less than the estimate I'd mentally prepared for, and that number is the one I actually care about.

What I didn't know going in

I've refinanced once before, back in 2019, and nobody mentioned a second score then. I assumed the rules hadn't changed since. They had. Fannie Mae and Freddie Mac went through a long, slow-moving approval process to let lenders use VantageScore 4.0 as an alternative to the older FICO models, and it's been rolling out unevenly across lenders since. Some loan officers run both scores automatically. Others still default to the one model and won't think to check the second unless you ask. Mine only mentioned it because my FICO came in lower than the rate tier he wanted for me, which tells me plenty of borrowers are probably leaving money on the table without knowing it.

I called my sister, who bought a condo in March, and asked if her lender had done the same thing. She had no idea what I was talking about. Her lender never ran a second score, at least not that she was told about. Her rate might have been fine regardless, I don't actually know, but the fact that this isn't standard practice yet, nearly a year into the rollout, is the part that bothers me.

The part I got wrong

I used to think shopping for a mortgage meant comparing lenders and nothing else. Call three or four, get quotes, pick the lowest. I never once thought about which credit model a given lender defaults to, because I assumed a credit score was just a fact about me, not something that shifted depending on who was measuring it. That's naive, and I should have known better since I already knew my VantageScore and FICO didn't match when I checked them separately for curiosity a few years back. I just never connected that gap to anything that would show up on a mortgage rate sheet.

What I'd actually tell someone

• Pull both your FICO score (through a site like myFICO or your card issuer) and your VantageScore (Credit Karma, Chase sometimes shows it too) before you talk to anyone about a loan
• If there's a real gap between the two, mention it to your loan officer directly and ask which model they're running
• Don't assume every lender automatically checks both. Based on my sister's experience, plenty don't unless you push
• A lower FICO doesn't mean you're stuck with a worse rate if your VantageScore tells a different story
• This mostly applies to conventional loans through Fannie or Freddie. I don't know how FHA or VA loans handle this, so ask specifically if that's your situation

I'm not saying everyone will see a 31-point gap, or that it'll move your rate the way mine did. Some people check both scores and find they're nearly identical. Mine happened to be the lucky case where the gap mattered. But the fact that it mattered at all, and that I came one careless comment away from never hearing about it, is what's sticking with me. A $94 monthly difference is around $1,128 a year, and over a 30-year loan that's not nothing. I keep thinking about how close I came to never asking.

Rates are still sitting stubbornly near the mid-6% to low-7% range depending on the day and the lender, and nobody I follow seriously expects a dramatic drop soon. If you're shopping for a mortgage or a refi anytime in the next year, this feels like one of those small, specific questions worth asking out loud instead of hoping your loan officer brings it up first. Mine almost didn't.