Of everything that determines your mortgage rate, your credit score is the largest factor you can still influence in the months before you apply. Rates move with the bond market and you can't control that. Your score is different — and the way lenders use it makes small improvements occasionally worth a great deal.

Pricing works in tiers, not on a slope

This is the single most useful thing to understand. Mortgage pricing does not improve smoothly as your score rises. It improves in steps, at defined thresholds, and the industry convention is to place those thresholds at round numbers — commonly at 20-point intervals through the middle of the range.

The consequence is that where you sit relative to a threshold matters more than the raw number. Moving from just under a break to just over it can change your pricing tier. Moving a similar distance entirely within a tier changes nothing at all.

So the right question before applying is not "how do I raise my score?" but "am I just below a threshold, and can I get over it?" Ask a loan officer where the breaks fall for the specific programme you're considering. A few points of improvement can be worth more than months of general effort if it happens to cross a line — and worth nothing if it doesn't.

Lenders don't use the score you're looking at

The score in your banking app or credit card dashboard is usually not the one your mortgage lender sees. Mortgage underwriting has historically relied on older, specific versions of the FICO scoring models, pulled from all three major bureaus — which differ from the free consumer scores most apps display, and from each other.

Two practical consequences:

  • Expect a discrepancy. Your mortgage score may be meaningfully different from your app score in either direction. Don't build your plan on the free number.
  • Three bureaus, one decision. Lenders pull all three and typically use the middle score, not the best. With joint applicants they generally use the lower of the two applicants' qualifying scores, which means the stronger applicant's score doesn't rescue the weaker one.

That last point is worth planning around. If one applicant's score is materially weaker and the income of the stronger applicant alone would qualify, applying solo is sometimes the better structure. It's a real trade-off — one income versus better pricing — and worth modelling both ways.

What actually moves a score, ranked by speed

Payment history and credit utilisation are the two heaviest factors in most scoring models, and utilisation is by far the faster of the two to change.

  • Pay down revolving balances (fast — weeks). Utilisation is your balance relative to your limit, and it's recalculated as issuers report. Lowering it is the most reliable short-term lever available.
  • Pay before the statement date, not the due date (fast). Issuers usually report the statement balance. Paying in full every month but carrying a large statement balance still reports high utilisation. Paying down before the statement closes reports a lower figure — a genuinely underused trick.
  • Dispute genuine errors (weeks to months). Reporting mistakes are not rare. Check all three bureaus; an account that isn't yours, or a paid debt still showing as delinquent, can cost real money.
  • Become an authorised user (weeks). Being added to a well-managed long-standing account can help, depending on the model and whether the issuer reports authorised users.
  • Simply keep paying on time (slow — months to years). The most powerful factor and the one you cannot accelerate. A single late payment during the mortgage process is genuinely damaging.

What to leave alone before applying

Several intuitive moves are counterproductive in the months before a mortgage application.

  • Don't close old credit cards. It reduces your total available credit, which raises utilisation, and can shorten your average account age. The instinct to "tidy up" before applying often lowers the score.
  • Don't open new accounts. New credit adds an inquiry and lowers average account age. The store card offering a discount on appliances for the new house is a genuinely bad trade at this moment.
  • Don't finance a car. It adds a monthly obligation that raises your debt-to-income ratio as well as touching your score. This has sunk closings.
  • Don't pay off collections without asking first. Counterintuitive, but under some older scoring models paying a collection can update its date of activity unhelpfully. Ask your loan officer about your specific situation before acting.

Rate shopping doesn't wreck your score

A persistent fear, and largely unfounded. Scoring models treat multiple mortgage inquiries within a short window as a single event, precisely so consumers can compare offers without being penalised.

Concentrate your applications into a compact period rather than spreading them across months, and the inquiries count once. A single hard inquiry has a modest and temporary effect on a healthy file — far less than the cost of accepting a worse rate because you were afraid to compare. See pre-qualification vs pre-approval for how the application stages work.

Score isn't the only lever

Pricing adjustments are driven by a combination of factors, and score is one input among several. Your loan-to-value ratio matters — a larger down payment improves pricing independently of your score. So does property type, occupancy (a primary residence prices better than an investment property), and loan programme.

This matters when your score is stuck. A borrower who can't move up a tier may still improve their rate materially by increasing the down payment, or by comparing loan types. Different programmes weight credit differently, so a score that prices poorly on one may fare better on another.

A realistic timeline

If you're six months out, pull all three reports, dispute errors, and get balances down. If you're two months out, focus almost entirely on utilisation and on not doing anything new. If you're two weeks out, change nothing at all — just keep paying on time and don't touch your credit.

The bottom line

Mortgage pricing moves in tiers, so proximity to a threshold matters more than your raw score. The number your lender uses probably isn't the one in your app, and with joint applicants the lower score usually governs.

Paying down revolving balances before the statement date is the fastest legitimate lever. Closing cards, opening accounts, and financing a car before closing are the fastest ways to go backwards. And if your score won't move, a larger down payment can improve your pricing on its own.