UK mortgage rules: 4.5× LTI caps, stress tests, and SDLT

How the Bank of England and FCA mortgage rules determine your maximum borrowing capacity, repayment vs interest-only options, and Stamp Duty Land Tax.

Updated 2026-08-26 · Reviewed against official Bank of England and MoneyHelper regulatory guidance. · Fact-Checked Lending Norms

The 4.5× income multiple rule

Under Bank of England macroprudential limits, mortgage lenders in the UK are restricted in granting loans exceeding 4.5 times single or joint gross annual income. A maximum of 15% of high-volume residential mortgages can exceed this threshold under lender exception allowances.

FCA affordability stress test

Lenders test whether you can still afford repayments if mortgage rates rise by 3 percentage points above their Standard Variable Rate (SVR). They review net monthly income, credit commitments, childcare, and basic household expenditure.

Stamp Duty Land Tax (SDLT) planning

When budgeting deposit requirements, factor in Stamp Duty Land Tax. First-time buyers in England and Northern Ireland benefit from relief up to £425,000, while home movers pay tiered rates starting at £250,000. Second homes or buy-to-let properties incur a 3% to 5% surcharge.

Repayment vs interest-only mortgages

Capital-and-interest repayment mortgages guarantee the debt is paid off by the end of the term. Interest-only loans keep monthly payments lower, but require a credible repayment vehicle (such as investments, pension lump sum, or property sale) to repay the balance at maturity.

ℹ️ Statutory Notice & Methodology

Global Finance Calculator provides mathematical estimates for education, planning, and comparison — not regulated financial advice or credit pre-approval. Tax legislation, statutory central bank buffers, and underwriting criteria change. Confirm critical figures with official regulatory publications or a licensed mortgage broker before signing contracts.