Last reviewed: June 2026
TL;DR- There is no single universal credit score - Experian, Equifax and TransUnion each calculate their own scores, and lenders use their own proprietary scoring models.
- Lenders look at the detail of the credit file (specific accounts, payment history, adverse events) rather than the consumer-facing score from credit reference agencies.
- Key factors in mortgage credit assessment: payment history, outstanding balances, length of credit history, credit applications and adverse events.
- Checking your own credit file does not harm the score - only hard searches (from credit applications) affect it.
How Credit Scores Work for Mortgages
Credit scores are numerical summaries of creditworthiness generated by credit reference agencies (CRAs) - Experian, Equifax and TransUnion in the UK. Each CRA maintains its own database of credit information and generates its own score using its own model. The consumer-facing scores (shown in apps like ClearScore, Credit Karma and Experian's own app) are useful indicators but are not the scores lenders use.
Mortgage lenders have their own proprietary credit scoring models that use data from one or more CRAs plus other data sources (banking behaviour, application data). The lender's score takes into account the specific risk factors most relevant to mortgage lending - different from scores optimised for credit card or personal loan underwriting.
What Lenders Look at in the Credit File
Rather than relying solely on the aggregate score, experienced mortgage underwriters assess the detail of the credit file. Key factors include:
- Payment history: missed or late payments on any credit product in the last 1-6 years are the most negative factor for mortgage applications.
- Outstanding balances: high utilisation of available credit card limits (above 50-75%) negatively affects the assessment.
- Adverse events: defaults, CCJs, IVAs, bankruptcies are the most serious negative factors. Their recency, value and satisfaction status determine the impact.
- Financial associations: joint accounts or mortgages with partners whose credit is adverse create a financial link that affects assessment.
- Recent credit applications: multiple applications in a short period create multiple hard searches and signal financial distress.
- Electoral roll registration: being on the electoral roll at the current address is a positive signal and assists identity verification.
Improving Credit Before a Mortgage Application
Steps to improve credit before applying for a mortgage include: registering on the electoral roll at the current address; checking the credit file with all three CRAs and correcting any errors; ensuring all existing accounts are paid on time; reducing credit card balances to below 50% of the limit; avoiding new credit applications in the 3-6 months before the mortgage application; closing unused credit accounts that are not needed; and allowing time for adverse events to age. Six to twelve months of consistent financial management before application makes a meaningful difference to lender assessment.
The Impact on Mortgage Rates
A clean credit file does not automatically qualify a borrower for the very lowest rates - LTV, income and property type also affect the rate offered. However, adverse credit events significantly restrict lender choice and mean that only specialist adverse credit lenders are available, at materially higher rates. The rate improvement from resolving adverse credit can be substantial over the life of a mortgage.
Frequently Asked Questions
Does checking my own credit score affect my mortgage application?
No. Checking your own credit file or score is a soft search and does not appear on the credit file as a hard search. It has no impact on the credit score and is not visible to lenders. Only applications for credit (including mortgage applications) that result in a hard search affect the score and are visible to other lenders. Checking your own file regularly is recommended and has no negative consequence.
Which credit reference agency do mortgage lenders use?
Most mortgage lenders access data from multiple CRAs. Experian and Equifax are the most widely used. TransUnion is used by some lenders. Because different lenders use different CRAs, it is important to check your credit file with all three to ensure there are no errors or unexpected adverse entries on any of them before applying for a mortgage.
How long does a missed payment affect my credit file?
Missed or late payments are recorded on the credit file and remain there for six years from the date of the missed payment. Recent missed payments have a more significant negative impact than older ones. A single missed payment from five years ago has much less weight in a mortgage credit assessment than one from six months ago. Building a consistent track record of on-time payments over the 12-24 months before application is the most effective way to demonstrate creditworthiness despite past issues.
Can I get a mortgage if my credit score is low but I have no adverse events?
A low score with no actual adverse events (no defaults, no missed payments, no CCJs) is often an indication of thin credit - little credit history for the agencies to assess. This can arise for young borrowers, recent arrivals in the UK, or those who have always avoided credit products. Building a modest credit history - a credit card used regularly and paid in full each month - is the most effective way to improve a thin credit file. A specialist broker can also identify lenders who are more comfortable with thin file applicants.
