Over the Cap? LISA Calculator – Lifetime ISA vs Mortgage Spreadsheet (UK)
Home over £450k? Find out if withdrawing your LISA still saves you money.
£6.00
Found your home, but it costs more than £450,000? Your Lifetime ISA can't be used penalty-free — but withdrawing anyway can still save you money if it gets you a cheaper mortgage. This spreadsheet tells you which, in minutes, using your own numbers.
What it does
Compares 4 options side by side: keep both LISAs, withdraw yours, withdraw your partner's, or withdraw both
Works out the 25% charge, the cash you'd actually get, and how much of your own money you'd lose
Finds your mortgage band (LTV) for each option and pulls in your broker's rate quotes
Calculates interest over a 2- or 5-year fix and gives a plain-English verdict
Shows the deposit you need for every LTV band from 60% to 95%
Works out first-time buyer stamp duty for England & NI automatically
What you get
One spreadsheet (.xlsx) that works in Excel, Google Sheets and Apple Numbers. Fill in the yellow boxes and everything else calculates itself. Example figures are included so you can see how it works straight away.
Made by Mind Money Maps — a part-qualified ACCA accountant who's been through it as a first-time buyer.
Instant digital download. A planning tool only, not financial or mortgage advice. Rules as at October 2026.