Mortgage rates aren't a single number. The "6.23% average" reported by Freddie Mac each Thursday4 is the rate offered to a borrower with a strong credit profile — typically 740+ FICO with 20% down. The same lender on the same day will quote a 660-FICO buyer something materially higher, often 50–75 basis points above the headline rate. Three credit-score thresholds matter most for San Diego buyers: 620, 680, and 740. Hitting them — or just barely missing them — changes monthly payments by hundreds of dollars and lifetime interest by tens of thousands.
The thresholds and what they unlock
| Score | What it unlocks | Approximate rate offered |
|---|---|---|
| 500–579 | FHA only, 10% down required | +1.0–1.5% above market |
| 580–619 | FHA at 3.5% down; conventional generally not available | +0.5–0.75% above market |
| 620–639 | FHA, conventional becomes available with most lenders | +0.375–0.5% above market |
| 660–679 | Standard tier — most loan products available | +0.25% above best |
| 680–699 | CalHFA conventional access; better pricing | +0.125% above best |
| 700–739 | Strong tier; very competitive rates | +0.05–0.125% above best |
| 740–759 | Best-rate tier opens | Best market rate |
| 760+ | Some lenders offer additional discount | Best rate, occasional bps off |
The exact pricing varies by lender, by program, and by month. The pattern is consistent: every 20-point credit score band changes pricing meaningfully, and the impact is non-linear — moving from 720 to 740 is worth more than moving from 800 to 820.
The three thresholds that matter most
620: the conventional-loan threshold
Below 620, most lenders won't approve a conventional loan at all.1 You're effectively limited to FHA, which works but carries permanent mortgage insurance (MIP for the life of the loan if down payment is below 10%). FHA's 0.55% annual MIP on a $700,000 loan is roughly $321 per month — a permanent monthly cost that conventional PMI eliminates once you hit 80% LTV.
If you're hovering at 615–619, the marginal benefit of pushing your score above 620 is significant. A 5-point improvement can save $300+ per month in MIP for the life of the loan.
680: the comfortable-conventional threshold
At 680+, you have access to virtually every conventional loan product, including CalHFA programs and most jumbo lenders. Below 680, you can technically qualify for conventional but pricing is notably worse. The 660–679 range is where lenders apply "loan-level price adjustments" (LLPAs) — fees that effectively raise your rate by 25–50 bps.2
740: the best-rate threshold
This is where lenders stop charging premium adjustments and start offering their best advertised rates. The gap between a 720-credit borrower and a 740-credit borrower on the same loan is typically 25–37.5 bps — not huge in isolation, but meaningful over the life of the loan.
The dollar impact of each threshold
Same loan amount ($700,000), same purchase, same down payment. Different credit scores yielding different rates:
| Credit score | Approx rate | Monthly P&I | Lifetime interest |
|---|---|---|---|
| 620 | 6.85% | $4,587 | $951,253 |
| 660 | 6.55% | $4,448 | $901,107 |
| 700 | 6.35% | $4,356 | $868,034 |
| 740 | 6.23% | $4,301 | $848,331 |
| 760+ | 6.13% | $4,256 | $831,993 |
The gap between 620 credit and 740+ credit on the same $700K loan is roughly $286 per month — or $102,900 over the life of the loan. That's a real number, and it's the case for every hundred-point credit score improvement compounding the same way.
Credit score and loan-to-value ratio interact. A 740-credit buyer with 20% down gets the best rate. A 620-credit buyer with 5% down gets the worst pricing on every dimension — higher rate, higher PMI premium, higher loan-level adjustment. Improving credit before applying often unlocks not just a better rate but better PMI pricing too.
How to move from one threshold to the next
Five tactics that consistently improve scores in the 30–90 day window before applying:
1. Pay down credit card balances
Credit utilization is roughly 30% of your FICO score. The optimal target is below 30% on each individual card and below 10% across all cards combined. A buyer carrying 60% utilization across multiple cards can often gain 20–40 points within 30–60 days simply by paying balances down.
The catch: pay them down, but don't close the cards. Closing a long-held card reduces your average account age and can drop your score 10–30 points temporarily.
2. Don't open new accounts
New credit accounts trigger inquiries, lower your average account age, and reduce your score. The 6 months before a mortgage application are the worst possible time to open a new credit card, finance a car, or co-sign a loan for a family member. Don't.
3. Dispute legitimate errors
Roughly 1 in 5 consumers has a material error on at least one of their three credit reports.3 Pull all three reports for free at AnnualCreditReport.com and dispute anything that's:
- Not yours (mistaken identity, including family members with similar names)
- Reported incorrectly (a paid-off debt still showing as outstanding, a $50 late payment shown as 90 days late)
- Past the 7-year reporting limit (or 10 years for bankruptcies)
Successful disputes typically resolve in 30–45 days and can boost scores 20–80 points.
4. Catch up on past-due accounts
Bringing a late account current immediately stops the damage but doesn't reverse it — a 60-day-late notation stays on your report for 7 years. However, paying off collections via a "pay for delete" agreement (where the collector agrees in writing to remove the account upon payment) can significantly improve scores. Get the agreement in writing before paying.
5. Keep old accounts open and lightly used
Average account age is 15% of your score. A credit card you've held for 12 years and use occasionally is a credit-score asset. Don't close it just because you don't use it heavily.
What hurts faster than you'd expect
Three actions that cost score points quickly, and that buyers consistently underestimate:
- Co-signing for a family member. The full debt and any late payments hit your credit report exactly as if it were your debt. A co-signed auto loan that's 30 days late drops your score 60–100 points.
- "Hard inquiries" stacking up. Each new credit application generates a hard inquiry. One inquiry costs 5–10 points. Five inquiries in 6 months can cost 25–40.
- A single missed payment. One 30-day-late credit card payment on an otherwise clean profile can drop your score 60–110 points and stays on your report for 7 years.
The right time to pull your credit
Your lender will pull a tri-merge mortgage credit report — a different beast than the FICO score you see on your credit card app or Credit Karma. Three points:
- Mortgage credit reports use FICO Model 5, 4, and 2 (Equifax, TransUnion, Experian). Credit card apps and free monitoring tools usually show FICO 8 or VantageScore. The mortgage scores are typically lower than what you've been seeing — sometimes 20–40 points lower.
- Lenders use the middle of the three scores. If your three scores are 715/735/750, the lender uses 735 for pricing.
- Mortgage credit pulls have a 45-day "rate shopping" window. Multiple mortgage inquiries within 45 days count as one inquiry for FICO scoring, allowing you to shop lenders without compounding score damage.
See your San Diego scenario at different rate scenarios.
Open the calculator →The honest read
Credit score is one of the few mortgage variables you can materially improve in 60–90 days through deliberate action. The gap between 620 and 740+ credit on a typical San Diego loan is approximately $300 per month and $100,000 over 30 years — well worth a focused 3-month effort to push your score up before applying. Pay down balances, don't open new accounts, dispute errors, and pull your reports yourself before the lender does. The thresholds (620, 680, 740) are real, the rate differences between them are real, and most buyers aren't optimizing carefully enough.
Rate quotes vary by lender, day, and individual file. Score-impact estimates are typical but vary by individual credit profile. Educational content only — not legal, tax, or financial advice.
References
- Fannie Mae. (n.d.). Selling Guide B3-5: Credit assessment. Retrieved April 28, 2026, from https://selling-guide.fanniemae.com/sel/b3-5/credit-assessment
- Federal Housing Finance Agency. (2023). Loan-level price adjustments (LLPAs). Retrieved April 28, 2026, from https://www.fhfa.gov/policy/loan-level-pricing-adjustments
- Federal Trade Commission. (2013). Report to Congress under Section 319 of the Fair and Accurate Credit Transactions Act of 2003. Retrieved April 28, 2026, from https://www.ftc.gov/reports/section-319-fair-accurate-credit-transactions-act-2003-fifth-interim-federal-trade-commission
- Freddie Mac. (2026, April 23). Primary Mortgage Market Survey: U.S. weekly mortgage rate averages. https://www.freddiemac.com/pmms