Guide
How your credit score changes your mortgage rate
Credit pricing moves in tiers, not on a smooth curve. Landing four points below a threshold can cost more than most people expect.
Most people assume mortgage pricing treats credit as a slope: a little better score, a little better rate. It does not. It treats credit as a staircase, and where you stand relative to the next step matters far more than the raw number.
The staircase, not the slope
Conventional loans backed by Fannie Mae and Freddie Mac are priced using a published grid of loan-level price adjustments — LLPAs. The grid is two-dimensional: your credit score bucket on one axis, your loan-to-value on the other. Each cell contains a cost, expressed in points.
The buckets have hard edges. Common breakpoints sit around 620, 640, 660, 680, 700, 720, 740, and 760+. A 739 and a 740 are one point apart as numbers and one full tier apart as prices.
This is why the single most valuable question before you apply is not "is my credit good?" but "how far am I from the next threshold up?"
The cost compounds with your loan-to-value
The second axis is the one people miss. The penalty for a lower score is not fixed — it grows as your down payment shrinks.
At 60% LTV, dropping a credit tier might cost you a fraction of a point. At 95% LTV, the same drop can cost several times that. The logic is straightforward from the investor's side: a weaker borrower with substantial equity still has a strong incentive and a cushion to sell into. A weaker borrower with almost no equity has neither.
Two consequences follow:
- If your score is marginal, a slightly larger down payment can be worth more than it looks, because it moves you on both axes at once.
- If your score is strong, the marginal value of extra down payment is smaller, and cash may be better kept in reserve.
Mortgage insurance is priced off the same score
If you put less than 20% down on a conventional loan, you pay private mortgage insurance — and PMI is priced off credit and LTV too, on its own grid.
So a borrower below 20% down takes the credit hit twice: once in the rate through LLPAs, once in the monthly PMI premium. This is the situation where a modest score improvement pays back fastest, and it is worth modelling before you lock anything.
FHA works differently. Its mortgage insurance premium is not credit-scored the same way, which is precisely why FHA is often the better arithmetic for a lower-score borrower even though its insurance is harder to remove later. Which loan wins is a calculation, not a rule of thumb.
Which score they actually use
Not the one in your banking app. Mortgage lenders pull a tri-merge report — all three bureaus — and use scoring models built specifically for mortgage lending, which differ from the consumer-facing versions most free services show.
With three scores in hand, the convention is to use the middle one. If two borrowers are on the loan, most conventional programs use the lower of the two middle scores. That means the weaker credit profile on a joint application generally sets the price for both.
It is worth knowing this before you assume a co-borrower helps. Adding income helps debt-to-income. Adding weaker credit can cost you a tier.
What actually moves a score before closing
If you are within reach of a threshold, a few levers work on a timescale that matters:
- Pay down revolving balances. Utilisation is heavily weighted and updates when the card reports, so this is the fastest legitimate lever. Getting each card under roughly 30% — and the overall figure lower still — can move a score in one cycle.
- Do not close old accounts. Age of credit history and total available credit both matter. Closing a card you no longer use shortens one and shrinks the other.
- Do not open anything new. No car loan, no furniture financing, no store card. Not before applying, and not between application and closing — lenders re-pull before funding, and a new account can reprice or sink a loan days before it closes.
- Dispute genuine errors early. Corrections take time to propagate. Start before you apply, not during underwriting.
The honest caveat
None of this predicts your rate. LLPA grids are published and change; lender margins differ; the market moves daily. The value of understanding the staircase is knowing which lever to pull before you apply, when pulling it is still cheap.
If you want to know which tier you currently land in and what the next one up would actually save on your loan amount and down payment, Bloom Lending can run both scenarios side by side before you commit to anything.