Lifetime ISA Calculator
Calculate your LISA growth with the 25% government bonus for 2025/26. Compare LISA vs regular ISA, see your projected pot for a first home or retirement, and understand the early withdrawal penalty.
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How to Use This Calculator
LISA Growth tab
Enter your monthly contribution (max ~£333/month to stay within the £4,000 annual limit), your current age, and choose whether you're saving for a first home or retirement. The calculator projects your total pot including the 25% government bonus and investment growth, with a year-by-year breakdown table.
LISA vs Regular ISA tab
Compare a Lifetime ISA (with the 25% bonus but withdrawal restrictions) against a regular Cash ISA (no bonus but full flexibility). See how much extra the LISA earns over time, and what the cost would be if you needed to withdraw early and trigger the 25% penalty.
First Home vs Retirement tab
Explore the opportunity cost of using your LISA pot for a first home deposit versus leaving it invested until age 60. See how much compound growth you give up by withdrawing early for a property, and whether the deposit benefit outweighs the retirement savings loss.
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The Formula
Lifetime ISA growth combines your contributions, the government bonus, and compound investment returns:
Annual Bonus = Annual Contribution × 25% (max £1,000)
Each year: Balance = (Previous Balance + Contribution + Bonus) × (1 + Growth Rate)
Early Withdrawal Penalty = Total Withdrawal × 25%
Net received = 75% of total pot
Effective loss = Government bonus + 6.25% of your own money
The 25% early withdrawal penalty is applied to the total amount withdrawn, not just the bonus. Because the bonus makes up 20% of your pot (£4,000 contribution + £1,000 bonus = £5,000 total, bonus is 20%), taking 25% of the total means you lose all the bonus plus 6.25% of your own contributions.
For example: contribute £4,000, receive £1,000 bonus = £5,000 pot. Withdraw early: penalty = £5,000 × 25% = £1,250. You receive £3,750 — that's £250 less than your £4,000 contribution.
Example
Emily — Marketing Manager, 25, saving for her first home at 30
Emily earns £35,000 and saves £333/month into a Lifetime ISA. She plans to buy her first home in 5 years, with a 4% expected growth rate on her S&S LISA.
Year-by-year breakdown
Emily's LISA pot of £28,138 includes nearly £5,000 in free government money. If she buys a property under £450,000, she can use the entire pot penalty-free as her deposit. On a £300,000 home, that's a 9.4% deposit.
If Emily instead needed to withdraw early for a non-qualifying purpose, the 25% penalty would cost her £7,035, leaving just £21,104 — £1,124 more than her original contributions but significantly less than the Cash ISA alternative.