Understanding Your Credit Score: What UK Lenders Actually Look At
Quick answer: UK lenders don't see one universal "credit score" — Experian, Equifax and TransUnion each calculate their own number on different scales, and mortgage lenders use their own internal scoring on top of that data, not the score you see in an app. What actually matters across all of them is the same underlying record: payment history, credit utilisation, account age, and how many applications you've made recently. Improving those four things improves your standing with every lender, regardless of which score you're looking at.
The number shown in a free credit-checking app is a useful proxy, but it isn't what a mortgage underwriter actually reads. Understanding the underlying record matters more than chasing a specific score.
Why don't UK lenders use the score in my banking app?
The three UK credit reference agencies each run their own scoring model on their own scale — Experian scores out of 999, Equifax out of 1000, TransUnion out of 710. A "very good" score by one agency's scale looks nothing like another's, and no lender is contractually bound to use any of them directly.
Instead, most lenders — especially mortgage lenders — pull the raw data (not the branded score) from one or more agencies and run it through their own internal risk model, weighted for their own risk appetite. Two lenders can reach different decisions on the same applicant using the same underlying data, because their internal models weigh it differently.
What four factors actually drive every model, regardless of scale?
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Payment history — missed or late payments are the single biggest factor, and stay on your file for six years.
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Credit utilisation — the percentage of your available credit you're using. Below 30% is generally viewed favourably; above that, less so, even if you always pay in full.
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Account age and mix — longer-held accounts and a mix of credit types (credit card, loan, mobile contract) tend to score better than a thin, brand-new file.
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Recent applications — several credit applications in a short window (a "hard search" cluster) signals higher risk to a model, even if every application was approved.
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Credit limit across all cards: £5,000
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Current balance across all cards: £2,200 → Utilisation: 44% — above the commonly cited 30% threshold, worth paying down before a mortgage application
What should you actually do before applying for a mortgage?
Check your report with at least one agency (Experian, Equifax, and TransUnion all offer free access) and correct any errors — a wrong address or a mistakenly listed missed payment is more common than people expect, and disputing it is free. Pay down utilisation below 30% where you can, avoid opening new credit in the 3-6 months before applying, and make sure you're on the electoral roll at your current address, since lenders use it to verify identity.
Once your file is in good shape, check what that actually means for what you can borrow with the Affordability Calculator — your credit standing affects the rate you're offered, which changes the real monthly cost of any mortgage you're considering.
This article explains how UK credit scoring generally works and is not financial advice specific to any individual's circumstances or a guarantee of any lender's decision.
See What You Can Actually AffordOnce your credit file is in shape, find out what it means for the mortgage rate and amount you could be offered.Try the Affordability Calculator