Lifetime ISA calculator

How much will my Lifetime ISA be worth?

Enter your age, what you pay in each month and the growth you want to assume, then pick how the money comes out: toward a first home, kept until 60, or withdrawn early for another reason. The calculator adds the 25% government bonus to every payment, compounds the account monthly and takes off whichever withdrawal charge applies to that route.

On the defaults, £250 a month from age 30 is £3,000 a year, which earns £750 a year of bonus. With an assumed 4% a year, the account holds £20,680.94 after 5 years: £15,000 of your money, £3,750 of bonus and £1,930.94 of growth. A first home at £300,000 is inside the £450,000 cap, so all £20,680.94 goes toward the purchase.

The headline always shows what you would actually receive, after any charge. The Other withdrawal tab shows the same account taken out early, which is where the 25% charge bites.

Lifetime ISA rules for 2026/27

Every figure here comes from GOV.UK's Lifetime ISA guide and HM Treasury's government response of October 2026, read on 14 November 2026.

For a first home without a charge, GOV.UK sets further conditions: you buy at least 12 months after your first payment, you buy with a mortgage, and a conveyancer or solicitor acts for you, with the provider paying them directly. The calculator checks the price against the cap and the age limits; the other conditions are yours to meet.

How does the Lifetime ISA withdrawal charge work?

The 25% charge is taken from the whole amount you withdraw, and that amount already includes the bonus. That is why it costs more than the bonus it is meant to recover. Every £100 you pay in becomes £125 with the bonus. A quarter of £125 is £31.25, so you get £93.75 back: the £25 bonus is gone, and so is £6.25 of your own money, a 6.25% loss before any growth.

GOV.UK gives the same arithmetic with real amounts. Savings of £800 earn a £200 bonus, making £1,000. Withdrawing it all brings a £250 charge and leaves £750, which is £50 less than was paid in. On the calculator's defaults with no growth, 5 years of £250 a month gives £18,750, and an early withdrawal leaves £14,062.50, or £937.50 below the £15,000 you contributed.

For a partial withdrawal, you must take out enough extra to cover the charge. To be left with a set amount, divide it by 0.75: GOV.UK's example withdraws £160 to receive £120, and receiving £1,000 means withdrawing £1,333.33. Growth can hide the loss: at an assumed 4% for 5 years the default account reaches £20,680.94, and the 25% charge still leaves £15,510.71, a little above the money paid in.

What if my first home costs more than £450,000?

Until 29 October 2026, buying above the cap counted as an ordinary unauthorized withdrawal, with the full 25% charge. HM Treasury's government response, published on 28 October 2026, kept the £450,000 cap but cut the charge to 20% for purchases above it that meet every other qualifying rule. HM Revenue and Customs confirmed in its tax-free savings newsletter of 29 October 2026 that the reduced charge applies to eligible withdrawals made on or after that date and not to earlier ones.

A 20% charge takes back exactly the bonus at zero growth: £125 less 20% is £100, the amount you paid in. On the defaults, a £500,000 home leaves £16,544.76 of the £20,680.94 account after a £4,136.19 charge, against £20,680.94 for a home at £450,000 or less. Change the price in the calculator to see the step at the cap: £450,000 exactly is still inside it.

Is the Lifetime ISA being replaced?

A replacement is announced but not yet in force, and the government says it will now put the legislation in place. HM Treasury's consultation on a First Time Buyer ISA closed on 18 August 2026, and its government response was published on 28 October 2026. It says a First Time Buyer ISA will be introduced from April 2029 and offered in place of the Lifetime ISA, and that Lifetime ISA accounts opened until then can continue under their existing terms.

The response sets out the new account's design: up to £4,000 a year, a 25% bonus worked out on the final balance and paid only when the money goes toward a first home, an overall bonus limit of £20,000, the same £450,000 price cap, no withdrawal charge, and no upper age limit for opening one. Unlike the Lifetime ISA, its bonus is tied to buying a first home. Money cannot be transferred from a Lifetime ISA into the new account, though both can go toward the same purchase.

This calculator models the Lifetime ISA as it works today. Its rules file is dated, so the figures are updated in one place if the government changes them again.

First home or age 60: how the two uses compare

The Hold to 60 tab runs payments until 50 and growth until 60, with no charge at the end. At the full £4,000 a year from age 30, you pay £80,000, receive £20,000 of bonus, and at an assumed 4% the account reaches £224,406.10 at 60. At £250 a month instead, it reaches £168,304.58. Starting at 35 with £4,000 a year gives 15 years of payments and £150,896.75 at 60.

For a home, time is shorter but the bonus counts for more of the result: on the 5-year default, the bonus is £3,750 and growth only £1,930.94. Over the 30 years to 60, growth becomes the larger share. In both cases the 25% bonus is a fixed top-up on each payment, while the growth figure is an assumption that markets may not match.

How payments, growth and time move the result

Holding the default £250 a month toward a first home:

• Assumed growth. After 5 years the account holds £19,693.40 at 2%, £20,680.94 at 4% and £21,714.31 at 6%. The bonus is the same £3,750 in each case.
• Time. At 4%, it holds £11,919.09 after 3 years, £20,680.94 after 5 and £45,842.48 after 10.
• Payments. Every pound you pay in up to £4,000 a year adds 25p of bonus. Anything above the limit gets no bonus, and the calculator leaves it out and says so.
• Other ISAs. If cash or stocks and shares ISAs already take more than £16,000 of the £20,000 allowance, the room left for the Lifetime ISA shrinks to match.

Age changes the answer in two ways. At 40 or over with no account, you cannot start one, so the calculator adds nothing. Anyone already holding one can pay in until 50; after that, the account only grows.

How to work out a Lifetime ISA in Excel

Treat each month's payment plus its bonus as one payment, then use Excel's FV function. For £250 a month the combined payment is £312.50. Convert the yearly growth to a monthly rate with =(1+0.04)^(1/12)-1, which is about 0.3274% a month, then =FV(A1, 60, -312.5) with that rate in A1 returns 20,680.94, matching the calculator.

For the withdrawal, multiply the value by 0.75 for the 25% charge or 0.8 for the 20% charge. To find the gross withdrawal needed for a cash amount after the 25% charge, divide by 0.75. Cap the payment cell with MIN(planned yearly payment, 4000) so the spreadsheet never adds bonus above the limit.

What this calculator leaves out, and common mistakes

It adds the bonus at the same time as each payment, which is a simplification of how providers claim it. It uses one growth rate after charges for every year, does not model a cash Lifetime ISA's interest rate changes, and treats ages in whole years. It does not check the mortgage, conveyancer or 12-month conditions, and it does not model the terminal illness route, transfers, or the First Time Buyer ISA due from April 2029.

• Counting the bonus as yours before you qualify. An early withdrawal returns less than you paid in when growth is low.
• Starting too late. The first payment has to be made before 40, and a home purchase must come at least 12 months after it.
• Forgetting the overall allowance. The £4,000 sits inside the £20,000 ISA limit, not on top of it.
• Ignoring the price cap. A home at £450,001 brings the 20% charge.
• Paying more than £4,000. The extra earns no bonus.

Glossary

Lifetime ISA: a UK ISA for people who open it between 18 and 39, for a first home or later life. Government bonus: 25% added to payments, up to £1,000 a year. Unauthorized withdrawal: taking money out for a reason that does not qualify, which brings the 25% charge. Property price cap: the £450,000 limit for a charge-free first-home purchase. Conveyancer: the professional who handles the legal side of buying a home. First Time Buyer ISA: the account the government says will be offered in place of the Lifetime ISA from April 2029.

Frequently asked questions

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