UK Mortgage Calculators & Guides
Free tools for UK homeowners based on FCA regulations, Bank of England base rates, and MoneyHelper guidelines. No sales pitch, just transparent math.
UK Mortgage Overpayment Tools
UK mortgages have different rules than US loans. Most fixed-rate deals include a 10% annual overpayment allowance and charge Early Repayment Charges (ERC) if you exceed it. Our calculators use FCA-compliant formulas.
UK Mortgage Overpayment Calculator →
Calculate how much you can overpay without ERC penalties. See interest saved in £ and years cut from your term using your lender’s 10% allowance. Includes Bank of England base rate scenarios.
- ✓ Checks 10% annual allowance automatically
- ✓ Calculates ERC from 1% to 5% based on your deal
- ✓ Shows monthly vs lump sum overpayment impact
- ✓ Updated for BoE base rate: 5.25% (July 2026)
Key UK Mortgage Rules Explained
Understanding these FCA rules prevents costly mistakes. All guides below cite FCA and MoneyHelper sources.
10% Overpayment Allowance
Most UK fixed-rate mortgages let you overpay 10% of the outstanding balance per year without penalty. On a £200,000 mortgage, that’s £20,000/year. Exceed it and ERC applies. Learn how ERC is calculated →
Early Repayment Charge (ERC)
ERC is typically 1-5% of the amount overpaid above your allowance. It reduces each year of your fixed term. Year 1: 5%, Year 2: 4%, etc. Some tracker mortgages have no ERC. See ERC examples →
Offset Mortgages
Your savings balance offsets your mortgage for interest calculation. £20,000 in savings against £200,000 mortgage = interest charged on £180,000. Different from overpaying. Compare offset vs overpayment →
Porting Your Mortgage
Moving house? “Porting” lets you transfer your existing rate to a new property to avoid ERC. Conditions apply. Porting rules explained →
UK vs US: Critical Differences
| Feature | UK Mortgages | US Mortgages |
|---|---|---|
| Prepayment Penalty | ERC of 1-5% if you exceed 10% allowance | No penalty on conforming loans after 2014 |
| Term | 25-35 years typical, but fixed rate for 2-5 years only | 30-year fixed rate for entire term |
| Regulator | FCA | CFPB |
| Interest Calculation | Daily interest, annual statements | Monthly amortization, monthly statements |
Our UK Research Methodology
All UK calculators and guides are built using primary sources:
- FCA MCOB Rules — For overpayment and ERC regulations
- Bank of England Statistical Database — For base rate and average mortgage rate data
- MoneyHelper — UK Government’s free mortgage guidance
- HMRC — For mortgage interest tax relief rules
Last verified: July 20, 2026 against FCA Handbook MCOB 12.3 and BoE July 2026 Monetary Policy Report.
Disclaimer: I am a software developer, not an FCA-authorised advisor. This site provides educational tools based on public FCA, BoE, and MoneyHelper data. It does not constitute financial advice. Always verify critical decisions with your lender and an FCA-authorised mortgage advisor. Calculations assume standard UK fixed-rate terms.
