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Mortgage lenders don’t use the credit score you see in a banking app or a free credit-checking tool. That score is calculated by the app’s provider for its own purposes. What a lender actually uses is your credit report, pulled from one or more of the three UK credit reference agencies, run through the lender’s own internal scoring and underwriting rules.
The three agencies, and why their scores differ
Experian, Equifax and TransUnion each hold their own version of your credit history. They don’t always hold identical data, since not every lender or provider reports to every agency, and each one calculates its score using its own formula and scale. That’s why the same person can see three different numbers on the same day, none of which is “the” mortgage score, because none of them is used directly by a lender in that form.
What lenders actually request
When you apply for a mortgage or remortgage, the lender (or its underwriters) requests a credit report from at least one agency. They then apply:
- Their own internal scoring model, weighted towards what that lender considers relevant
- Their own lending criteria, covering things like recent CCJs, defaults, arrears or insolvency
- Affordability checks based on your income, committed outgoings and a stress test against higher interest rates
Two lenders looking at an identical credit report can therefore reach different decisions, because the report is only the raw material. The scoring and criteria applied to it are set by each lender individually, and none of that is published.
Why your consumer app score doesn’t map to a lender’s decision
| What you see | What it actually is |
|---|---|
| A number out of a scale, e.g. “Good” or “Fair” | A score built by the app or agency for consumer use, not a lender’s model |
| One agency’s score | A partial view, since lenders may use a different agency or several |
| A soft-search eligibility check | Not visible to other lenders, and not the same process as a full mortgage application |
| A hard-search mortgage application | Visible to other lenders, and the point where the lender’s own scoring is actually applied |
This gap is why someone can be told their score is “excellent” by an app, then still be declined by a particular lender, or the reverse: turned down by one lender based on its own criteria, then accepted by another that weighs the same report differently.
Soft searches versus hard searches
Checking your own report, or using an eligibility checker before you apply, is a soft search. It’s invisible to other lenders and doesn’t affect your file. A full mortgage application involves a hard search, which is recorded on your file and visible to other lenders. Our guide on soft and hard credit searches covers this in more detail, including why a mortgage in principle sometimes uses a soft search and sometimes a hard one, depending on the lender.
Why this matters more once there’s something on your file
The gap between an app’s score and a lender’s own assessment matters most once your file has something on it: a missed payment, a default, a CCJ, or an IVA or bankruptcy. A consumer app might mark your score down heavily for any one of these, using a simplified model, while an individual lender’s own criteria might weigh the same item quite differently, depending on how old it is, whether it’s satisfied, and what the rest of your file looks like. Neither the app’s verdict nor a single lender’s decision tells you what every lender would think.
This is also why being declined by one lender, often shown to you as a low “score” or a generic decline letter, doesn’t mean the same application would fail everywhere. Different lenders’ underwriting, and the agency or agencies they use, can produce genuinely different outcomes from the same credit history.
What actually goes into a lender’s own scoring
Beyond the credit report itself, lenders typically weigh:
- The loan-to-value (LTV) of the mortgage or remortgage, since borrowing a smaller share of the property’s value generally widens the options available
- Income and committed outgoings, assessed against a stress test at a higher interest rate
- How recent any adverse item is, and whether it’s marked satisfied or settled
- Employment type, with some lenders asking for extra documentation from self-employed applicants
None of this is published as a formula, and it varies between lenders, which is another reason a single consumer score can’t predict a mortgage outcome on its own.
Checking what a lender would actually see
Since the score in an app isn’t what matters, it’s worth looking at your full credit report instead. Everyone can get a statutory credit report free from each of the three agencies, and checking more than one gives a fuller picture of what different lenders might see. If you have a CCJ, default or missed payment on file and want to know exactly when it’s due to drop off, the credit file date calculator works this out from the relevant date.
What this means for remortgaging with bad credit
If you’re looking at a bad credit remortgage, don’t rule yourself out, or assume you’re fine, based purely on an app’s score. What matters is what’s actually recorded on your report with the agency or agencies a lender uses, how recent it is, and your current affordability and loan-to-value. Because lenders vary so much in how they weigh the same information, someone declined by their existing lender’s underwriting may still have options with a lender or specialist adviser used to assessing self-employed applicants or adverse credit more broadly.
If any of this is tied to wider money difficulties rather than a one-off event, free guidance from MoneyHelper or StepChange can help before you take on new borrowing. Otherwise, a specialist adviser can look at your actual report, rather than an app’s score, and talk through realistic options.
Frequently asked questions
Do all mortgage lenders use the same credit score?
No. Each lender builds its own scoring model on top of the credit report it receives, and each of the three main agencies (Experian, Equifax and TransUnion) calculates a different score on a different scale. That means the same credit history can produce different outcomes depending on which lender, and which agency's report, is used for a particular application.
Why is my score different in every app?
Each agency holds slightly different data, since not every lender or provider reports to every agency, and each uses its own scale and formula to turn that data into a number. An app showing an Experian-based score won't match one built on an Equifax or TransUnion report, even if checked on the very same day.
Can a mortgage lender see scores from all three agencies?
Usually a lender works mainly from one agency's report, though its process may involve checking more than one in some cases. Because coverage and detail can differ between agencies, some advisers suggest checking your own report with all three before applying, so nothing on file comes as a surprise.
Does a mortgage search show up as one score to the lender?
No. The lender receives your underlying credit report and runs its own scoring and underwriting rules against that data directly. What you see as ‘your score’ in a consumer app is a separate calculation built for a different purpose, and plays no direct part in how a mortgage lender actually assesses you.