Check your credit score on three different apps in the same week and you'll get three different numbers — sometimes wildly different ones. Experian might put you at 850 out of a possible 999. TransUnion, using its own 710-point scale, might land you at 640. Equifax, which tops out at 700, might show something closer to 480. None of these numbers is wrong, exactly. None of them is what your bank actually looks at when you apply for a mortgage, either.
You Don't Have One Credit Score — You Have Three
The three UK credit reference agencies — Experian, Equifax and TransUnion (which absorbed the old Callcredit brand back in 2018) — each hold a slightly different file on you, because lenders don't all report to all three. A high-street bank like Halifax or NatWest typically reports to every agency; a smaller buy-now-pay-later provider or a niche subprime lender might only report to one, and some newer lenders skip the traditional agencies almost entirely in favour of open banking data. That gap is why your Experian file can show six active accounts while your Equifax file only lists four, and a default recorded by one agency can be entirely missing from another. Each agency then runs its own proprietary formula over whatever data it holds and produces a number — Experian's runs to 999, TransUnion's CreditView score tops out at 710, Equifax's caps at 700 — built mainly to keep you opening the app and checking in, not to reflect precisely what a mortgage underwriter will see. The three scales don't even map onto each other in any simple percentage way, which is exactly why comparing a "780 on TransUnion" against an "820 on Experian" tells you almost nothing useful. Treat the headline number as a rough temperature check rather than a grade, and you'll worry about it a lot less.
This is worth sitting with for a second: the number glowing on your phone screen was never sent to a single lender. What actually happens when you apply for credit is that the lender pulls your file — accounts, balances, missed payments, recent searches — and runs it through its own internal scorecard, built around the risk appetite of that specific product. A car finance company weighs recent behaviour differently to a mortgage lender assessing a 25-year commitment.
What Actually Moves the Number
Strip away the marketing gloss and the mechanics are fairly consistent across all three agencies, even if the exact weighting differs.
Payment History Is the Biggest Lever
Nothing moves a credit file faster than a missed payment, and nothing rebuilds one slower. A single missed payment reported to a CRA stays on your file for six years, full stop — there's no negotiating an early removal, whatever a "credit repair" service on Instagram promises you. One missed mobile phone bill from three years ago can knock well over 100 points off an Experian score overnight; a County Court Judgment does considerably more damage and takes considerably longer to fade from view. Pay everything on time for the next six years and the old missed payment eventually drops out of the calculation window entirely — that's the only real fix, and there isn't a faster one.
Credit Utilisation — the Ratio Lenders Actually Care About
Utilisation is the percentage of your available credit you're actually using at any given moment, and it matters more than most people assume. Sitting at 90% of your credit card limit signals financial strain even if you clear the balance in full every month, because the agency only sees the figure on your statement date, not your repayment habits behind it. Keep utilisation under 30% across all your revolving credit and the effect on your score is generally positive; push past 75% and most scoring models start marking you down hard, regardless of income. The fix that actually works — and it's one most people never think of — is asking your existing card provider for a credit limit increase without spending a penny more, which instantly lowers the ratio.
Account Age and the Mix of Credit You Hold
Average account age matters, which is precisely why closing your oldest credit card to "tidy up" your wallet is usually a bad idea. A card opened in 2016 does quiet, ongoing work for your file every month it stays open and in good standing; close it and your average account age drops overnight. Lenders also like to see a mix — a mortgage or car finance agreement sitting alongside revolving credit shows you can handle different repayment structures, whereas a file made up entirely of short-term buy-now-pay-later products reads as riskier, even with a spotless payment record.
Hard Searches vs Soft Searches
Every "check your eligibility" button that promises it "won't affect your score" is running a soft search, which only you can see. Actually applying for the product triggers a hard search, which every future lender can see for up to twelve months and which can knock a handful of points off your score each time it happens. Four or five hard searches within a short window looks like desperation to an underwriter, even when each individual application was perfectly sensible on its own — brokers routinely tell clients to stop applying for anything, including new mobile contracts, in the three months before completion.
The Electoral Roll Check Nobody Mentions
Registering to vote at your current address does more for your score than most people realise, because it's the easiest way for a CRA to confirm you actually live where you say you live. Come off the electoral roll — which happens automatically if you move and don't re-register — and Experian in particular tends to mark this down as an identity-verification gap. It costs nothing and takes about five minutes on gov.uk. There's genuinely no reason not to do it the same week you move house.
What Lenders Actually See (It Isn't Your Score)
Here's the part the consumer apps don't advertise: when you apply for a mortgage with, say, Nationwide, Nationwide doesn't ring up Experian and ask "what's this person's score?" It asks for the underlying data instead — account history, current balances, search history, any defaults or CCJs — and runs its own internal model, calibrated against its own book of past customers and its own appetite for risk under FCA affordability rules. That's why you can be told by ClearScore that you have an "excellent" score and still get turned down by one specific lender, while a different lender approves you the same week on exactly the same file. Every lender weights the same raw data differently: a car finance provider cares far more about recent payment behaviour on short-term credit than about a mortgage settled a decade ago, while a mortgage lender does almost the opposite. Two applicants with an identical Experian score of 900 can walk away from the same bank with completely different offers, simply because one has a thin file the bank's model treats as unproven and the other has years of varied, well-managed credit behind them. That's also why a decent mortgage broker is worth more than obsessing over three extra points on an app.
Under the FCA's Consumer Duty, in force since July 2023, lenders also have to show they've properly assessed affordability rather than leaning on the score as a single pass/fail gate — income, existing outgoings and current living costs all factor in alongside the credit file itself. A pristine credit score sitting next to unaffordable existing debt commitments will still get declined.
Myths That Refuse to Die
- Checking your own score does not harm it — that's always a soft search, regardless of which app you use.
- Being married to someone with poor credit does not merge your files, unless you've taken out joint credit together, which creates a "financial association" that does show up on both files.
- Paying off a debt in full doesn't erase it from your file instantly — a settled default still shows for six years from the default date, just marked as satisfied rather than outstanding.
- Having no credit history at all is not the same as having a good score. It often scores worse than a thin, well-managed file, because there's simply nothing for a lender's model to work with.
What a Realistic APR Range Looks Like by Score Band
Representative APR — the rate the FCA requires lenders to offer to at least 51% of accepted applicants — gives a rough sense of what different score bands translate to in practice, though the exact figure always depends on the individual lender's own model and the product itself.
- Excellent files (broadly Experian 961+) typically see personal loan APRs from around 6.9% to 9.9%, and 0% purchase credit cards are usually on the table.
- Good files sit more around 10% to 15% on personal loans, with standard credit cards landing somewhere between 19.9% and 24.9% representative APR.
- Fair files push into 18% to 29% on personal loans, and near-prime cards from providers such as Aqua or Vanquis commonly carry 29.9% to 34.9% representative APR.
- Poor files are often steered towards guarantor loans or other high-cost credit, where APRs of 39.9% to 49.9% are common — short-term credit can run considerably higher again.
That gap between the top and bottom band, on an identical £10,000 loan repaid over five years, is roughly the difference between paying £1,800 in interest and paying closer to £7,000. It isn't a rounding error.
Six Moves That Actually Shift Your Score
Set up direct debits for every credit commitment, even the small ones — a forgotten £8 subscription that bounces does more damage than most people expect for something so trivial. Register on the electoral roll at your current address if you haven't already. Ask for a credit limit increase on your oldest card and don't spend the extra headroom; the point is the ratio, not the money. Space credit applications at least three months apart where you can, and avoid applying for anything at all in the run-up to a mortgage application specifically. Consider Experian Boost or an equivalent scheme that adds evidence of regular bill payments — Netflix, council tax, that sort of thing — to your file, since these payments wouldn't otherwise show up at all. And check all three files, not just one, because a data error sitting on Equifax alone won't show up if you only ever look at your Experian app.
None of this is complicated. Most of it is boring, unglamorous admin — the kind of thing that's easy to put off for another six months. The six-year memory of a missed payment isn't, though, and that's really the whole story.