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UK Lifetime ISA Calculator

Free UK LISA calculator. Project tax-free growth with the 25% government bonus on contributions up to £4,000/year.

Published

UK Lifetime ISA growth with 25% government bonus.

Final value

Your contributions

Government bonus

Worked example

Pay in the full £4,000 a year for 10 years and the government adds its 25 percent bonus on every contribution. Your own money totals £40,000 and the bonus adds £10,000, so £50,000 of contributions go to work. At a 6 percent average annual return, with each year's money invested from the start, the pot grows to roughly £69,858. That is about £19,858 of tax-free growth on top of the contributions and bonus combined. The bonus is effectively an instant 25 percent uplift, which is hard to beat, but it only pays off if you use the money for a first home under £450,000 or wait until age 60.

Item Amount
Your contributions (10 years)£40,000
Government bonus (25%)£10,000
Tax-free growth at 6%£19,858
Final LISA value£69,858

How it is calculated

The tool applies the 25 percent government bonus to your contributions, so an annual £4,000 effectively becomes £5,000 going into the account. It then grows that boosted amount using the future value of an annuity-due, assuming each year's money is invested from the start and compounds for the remaining years. Your own contributions and the bonus are tracked separately so you can see how much of the final pot is free money. The £4,000 annual cap sits inside the wider £20,000 ISA limit, and you can only open and pay into a Lifetime ISA between ages 18 and 50. The crucial catch is the withdrawal rule: taking money out for anything other than a first home under £450,000 or reaching age 60 triggers a 25 percent penalty on the amount withdrawn, which is more than the bonus and leaves you worse off than a standard ISA, so the projection assumes you keep to the qualifying conditions.

Frequently asked questions

LISA penalty?
Withdrawing for any reason other than first home (under £450K) or age 60+ triggers a 25% penalty on the withdrawal. That is greater than the 25% bonus on contributions, so you actually lose money vs a normal S&S ISA.
Who can open a Lifetime ISA?
You must be a UK resident aged 18 to 39 to open a LISA. You can then continue contributing until the day before your 50th birthday, after which no further payments or bonuses are allowed, though the account stays open and continues to grow.
How does the LISA interact with the £20,000 ISA allowance?
Your LISA contributions count toward your overall annual ISA allowance of £20,000. So if you pay in the full £4,000 LISA limit, you have £16,000 remaining to split across other ISA types such as a stocks and shares ISA or cash ISA in the same tax year.
Can I use a LISA alongside the Help to Buy: Equity Loan scheme?
You can use a LISA to purchase a qualifying first home, but HMRC rules mean you generally cannot use a LISA bonus and a Help to Buy: Equity Loan on the same property purchase. Check with your conveyancer before committing, as the rules around combining government schemes are strict.

Related calculators

Sources

  1. HMRC — Income Tax Rates and Personal Allowances 2026/27, HM Revenue & Customs
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