# How credit scores are built and what actually moves them

> The UK has no single credit score: Experian, Equifax and TransUnion each model borrowers differently, lenders rescore applicants privately, and only a handful of levers genuinely move the numbers.

*Section: Business — By Marcus Vale (Editor-in-Chief & Business & Markets Editor) — Published July 11, 2026 — 4 min read*

Canonical URL: https://dailyjunction.co.uk/business/how-credit-scores-are-built-and-what-actually-moves-them
Tags: credit-scores, personal-finance, credit-reference-agencies, lending, borrowing

## Key takeaways

- Britain's three credit reference agencies score on incompatible scales — Experian out of 999, Equifax out of 1,000, TransUnion out of 710 — and none of those numbers is what a lender actually uses to decide.
- Defaults, county court judgments and missed payments stay on file for six years from the date they are registered, and a recent default costs far more than an old one because scorecards weight recency heavily.
- The reliable levers are electoral roll registration, keeping card balances well below limits, six years of clean payment history and spacing out hard searches; salary, savings and council tax never appear on the file at all.

The first thing to understand about your credit score is that you do not have one. You have at least three, calculated by three private companies from three overlapping but non-identical files, on three incompatible scales — and the number a lender actually uses when you apply for a mortgage or a credit card is none of them.

Britain's consumer credit files are held by three credit reference agencies: Experian, Equifax and TransUnion, all regulated by the Financial Conduct Authority. Banks, card issuers, utility firms and mobile networks report your account behaviour to some or all of them each month — balances, limits, payments made on time, payments missed. The agencies bolt on public records: electoral roll entries from your local authority, county court judgments from the Registry Trust, bankruptcies and individual voluntary arrangements from the Insolvency Service. From that raw file, each agency computes its own headline score. Experian scores out of 999, Equifax out of 1,000, TransUnion out of 710. A 750 is comfortable at TransUnion and mediocre at Experian, which is the first clue that the number itself is marketing as much as measurement.

The deeper point is that lenders do not borrow these scores. A bank buys the underlying file data and runs it through its own scorecard, built from the repayment histories of its own past customers and tuned to its own appetite. One lender's model may punish a thin file harshly; another courts exactly those borrowers at a higher price. This is why a rejection from one card issuer says little about your chances elsewhere, and why someone with a glowing Experian number can still be declined: the agency score and the lender's private score are answering related but different questions. The agency asks how you compare with the general population; the lender asks how people who looked like you performed on its own book.

What the file actually rewards is boring and slow. Payment history dominates every model, and the data runs six years deep. A default — registered when a lender gives up on an account, typically after three to six missed payments — stays on the file for six years from the default date, as does a CCJ, whether or not you later settle it. Recency matters as much as existence: scorecards discount a five-year-old default heavily and a five-month-old one barely at all. Utilisation is the second big lever — the share of your available credit you are using. Persistently maxed-out cards read as distress; balances kept under roughly a quarter to a third of the limit read as control. Electoral roll registration is the cheapest fix available, because it is how lenders confirm you live where you claim, and an unregistered applicant fails identity checks before creditworthiness is even assessed. Account age and stability round out the picture: long-held accounts and a settled address history score better than churn.

## The folklore, sorted from the mechanism

A great deal of what circulates as score advice is noise. Checking your own report never hurts it — a personal check is a soft search, invisible to lenders, unlike the hard searches recorded when you actually apply, which do sting slightly and sting more in clusters. Your salary is not on the file and neither are your savings; a lender learns your income from the application form, not from the agencies. Council tax and, historically, most rent payments go unreported, which is why a tenant who has never missed a payment can still carry a thin file, though rent-reporting schemes now feed some tenancies to the agencies. Closing old unused cards, often urged as tidiness, can lower a score twice over: it shortens the average age of accounts and shrinks total available credit, pushing utilisation up. And there is no blacklist of addresses — properties do not carry bad debt, people do. What an address can carry is a financial association: open a joint account or mortgage with someone and their file becomes relevant to yours until you ask the agencies for a notice of disassociation.

## What is genuinely worth doing

Strip the folklore out and the working list is short. Register to vote at your current address with all three agencies showing it. Pay every account on time, every month, on direct debit if discipline wobbles — one missed payment marks the file for six years. Keep card balances low relative to limits, and keep old clean accounts open. Space credit applications months apart, using eligibility checkers that run soft searches first. Check all three reports — each agency offers statutory free access — and dispute errors, because agencies must investigate within 28 days and lenders do act on corrected files. None of it is fast. That is rather the point: the file is a six-year memory, and the only strategy that consistently beats it is behaving, for a long time, like the borrower you are asking to be priced as.

---
Daily Junction — https://dailyjunction.co.uk/business/how-credit-scores-are-built-and-what-actually-moves-them