A Lifetime ISA calculator combines your contributions, the 25% government bonus, and growth assumptions so you can estimate potential value over time.
For planning, it helps to separate first-home timelines from long-term timelines, because access rules and risks are different.
Quick Answer: What a Lifetime ISA Calculator Should Show
Quick answer
A LISA calculator should show contributions, government bonus, and growth separately so you can see what part of the result is from each driver.
LISA Rules That Change the Projection
- Annual contribution cap is £4,000.
- Government bonus is 25% of qualifying contributions.
- Contribution cap counts within your adult ISA allowance.
- Withdrawal conditions affect how much value is usable for each goal type.
Official sources: GOV.UK Lifetime ISA and GOV.UK ISA rules.
Worked Example: Bonus and Growth Over Time
Illustrative run: £250 per month over 20 years with 5% return assumptions. The model shows total paid in, estimated bonus received, and projected growth separately.
Worked example: contribution, bonus, and growth
Illustrative
Assumes £250 monthly contribution, 25% LISA bonus, and 5% annual return over each horizon. Outcomes are illustrative only.
- Keep contribution and timeline fixed first.
- Compare 3%, 5%, and 7% assumptions as a range.
- Use this as a planning model, not a guaranteed outcome.
First-Home vs Retirement Planning View
First-home framing
Keep horizon shorter and return assumptions conservative, then check contribution pace against your target date.
Long-term framing
Use longer horizons and compare 3%, 5%, and 7% scenarios to see compounding sensitivity while keeping access restrictions in view.
How to Model Your Own LISA Scenario in NestBoost
Model your LISA scenario
Use the preset card above for direct scenario loading, then adjust contribution, timeline, and return assumptions in the calculator.
Check current GOV.UK guidance before making final contribution or withdrawal decisions.
FAQ
The Lifetime ISA contribution cap is £4,000 per tax year, and it counts inside your overall adult ISA allowance.
The bonus is 25% of qualifying contributions. Contributing £4,000 in a tax year can add up to £1,000 in bonus.
Yes. A Lifetime ISA can be modelled for first-home planning and longer-term saving, but access and withdrawal rules differ by use case.
Base projections often show growth only. You should separately account for potential withdrawal charges if funds are taken for non-qualifying reasons.