Methodology

Unmortgageable publishes guidance, timelines, and calculators that help people understand the UK mortgage market for their specific situation. Every figure is grounded in UK regulator data, lender criteria, or established statutory formulae. If a number on this site looks wrong, email us and we will review it.

Last reviewed: April 2026

Lender criteria and specialist lender categories

The “lender landscape” and “specialist lender” sections reflect the published criteria of UK mortgage lenders, alongside aggregate market data published by the Financial Conduct Authority, UK Finance, and the Bank of England.

Categorisation of lenders as “mainstream”, “near-prime”, or “specialist” is our editorial judgment based on the strictness of their published criteria. It is a simplification — the reality is a spectrum — but it is consistent across the site.

Credit recovery timelines

When we say something like “most specialist lenders open up 12 months after a CCJ is satisfied”, we mean it as a typical market indication, not a guarantee. The numbers come from UK specialist lender criteria, credit bureau retention rules under Information Commissioner’s Office guidance and the Steering Committee on Reciprocity, and the statutory insolvency framework set out in the Insolvency Act 1986.

Individual lenders within a category vary significantly. Our timelines reflect the median of UK specialist lender published criteria, not a best or worst case.

Affordability and repayment calculators

Our affordability estimator applies the FCA Mortgage Market Review standard stress test at an interest rate 3 percentage points above the lender’s standard variable rate, with the typical income multiples used across the UK market.

• Income multiples— between 4.0x and 5.5x household income depending on LTV and income level, reflecting the Bank of England’s loan-to-income flow limit (the “15% above 4.5x” cap) and typical lender policy variation.
• Repayment calculator — standard annuity repayment formula:M = P · [r(1+r)^n] / [(1+r)^n − 1] where M is monthly payment, P is principal, r is monthly interest rate (annual ÷ 12), and n is the total number of payments.
• Stamp duty — calculated from current HMRC Stamp Duty Land Tax rates for England and Northern Ireland, including the first-time buyer relief and the additional 5% surcharge for second homes. Scotland (LBTT) and Wales (LTT) are not currently modelled.

Bridging loan calculator

The bridging calculator uses typical market rates for regulated and unregulated bridging finance in the UK. Monthly interest is calculated as a simple monthly rate × loan amount × term in months. Arrangement fees are modelled at 1–2% of the loan amount based on market norms. Exit fees are assumed to be zero, which is standard for most bridging products but not universal — always check the specific lender’s offer document.

Lease extension estimator

Lease extension premiums are calculated using the statutory formula set out in the Leasehold Reform, Housing and Urban Development Act 1993 and updated by the Leasehold and Freehold Reform Act 2024. The calculation involves a diminution in value, marriage value (below 80 years unmarried), and compensation for freeholder losses. Our estimator is a simplification intended for rough planning only — always commission a formal valuation from a RICS-qualified surveyor before entering Section 42 negotiations.

Broker and service directory

Every broker and service listed on Unmortgageable is independently authorised by a relevant UK regulator (FCA for brokers and lenders, NAPB for cash buyers, RICS for surveyors). Where verified, each firm’s legal entity name and Firm Reference Number (FRN) are recorded so you can cross-check on the FCA Register before sharing personal details.

Inclusion is not an endorsement. We do not rank brokers by commission rate, we do not accept payment for higher placement, and we present all firms within a category in no particular order. Every broker card has a “Verify on the FCA Register” link so you can check them independently before sharing any personal details.

How often we update

Mortgage rates, lender criteria, government schemes, and regulations change frequently. We review each topic on the following cadence:

• Lender criteria and rates — reviewed quarterly and after any major Bank of England base rate decision.
• Stamp duty and government schemes — reviewed after every UK Budget and Spring Statement.
• Broker and service directory — reviewed quarterly; any firm that loses FCA authorisation or materially changes its fee structure is removed within 7 days.
• Credit bureau retention rules — reviewed annually or on regulatory change.

The footer of every article shows the last reviewed date. If a number on this site looks out of date, email hello@unmortgageable.co.uk and we will update it.

Corrections policy

When we update a figure or correct a factual error in a published article, the article is updated in place and its last-reviewed date is bumped. Material corrections are noted in the article so readers can see what changed and when.