ISA Allowance Calculator (2026/27)
The ISA allowance is £20,000 per tax year — use it or lose it, with no carry-forward. Enter what you have contributed so far to see how much room you have left before the 5 April deadline. The calculator tracks contributions across every ISA you pay into, including the £4,000 Lifetime ISA sub-limit that sits inside the overall total.
How it works
You can pay up to £20,000 per tax year across all your ISAs combined — cash, stocks & shares, innovative finance and Lifetime ISA in any mix. The Lifetime ISA has its own £4,000 sub-limit, which counts inside the £20,000 total.
A worked example: if you enter £13,500 already contributed this tax year, the calculator shows £6,500 of allowance remaining — simply £20,000 minus £13,500. If £4,000 of that £13,500 went into a Lifetime ISA, the LISA sub-limit is fully used, so the remaining £6,500 can go into cash, stocks & shares or innovative finance ISAs, but nothing more into the LISA until 6 April.
The allowance resets every 6 April and unused allowance is lost permanently — there is no carry-forward. Contributions count when made; withdrawals from most ISAs do not restore allowance unless the provider offers a "flexible ISA". Timing matters at the boundary: a payment made on 6 April falls into the new tax year's allowance, which is why some savers deliberately wait a day or two around the deadline.
Three mistakes catch people out. First, the £20,000 is a combined limit across every ISA you pay into, not a per-account limit — opening a second cash ISA does not create fresh allowance. Second, taking money out of a standard (non-flexible) ISA does not give the allowance back; paying it back in counts as a brand-new contribution. Third, the allowance measures money paid IN, not the value of the account — growth, interest and dividends arising inside the wrapper use none of it.
Interest, dividends and capital gains inside an ISA are entirely tax-free forever and never need reporting to HMRC. Since 2024 you can also pay into multiple ISAs of the same type in one year. Junior ISAs have a separate £9,000 limit that does not affect yours.
What the result covers: your remaining adult ISA allowance for the current tax year, based purely on what you tell it you have contributed. It does not track a child's £9,000 Junior ISA allowance (that belongs to the child and is separate), and it cannot know about flexible-ISA replacement rights — if your provider offers flexibility, money you withdrew and are replacing within the same tax year should not be entered as a fresh contribution.
FAQ
What is the ISA allowance for 2026/27?
£20,000 across all your adult ISAs combined — unchanged since 2017/18. Within that, a Lifetime ISA can take up to £4,000 (with a 25% government bonus if you are eligible). A separate £9,000 Junior ISA allowance exists per child and does not use up your own.
What happens to unused ISA allowance?
It disappears at midnight on 5 April — there is no carry-forward of any kind. This is why February and March see a rush of "use it or lose it" contributions. Even moving cash into an ISA without choosing investments protects that year's allowance.
If I withdraw money, can I pay it back in?
Only with a "flexible ISA": those let you withdraw and replace money within the same tax year without using fresh allowance. Standard ISAs do not — a withdrawal is simply gone, and re-depositing counts against your remaining £20,000. Check whether your provider offers flexibility before moving money.
Does the £4,000 Lifetime ISA limit come on top of the £20,000?
No — it sits inside it. Paying the full £4,000 into a Lifetime ISA (which attracts a 25% government bonus if you are eligible) leaves £16,000 of your overall allowance for cash, stocks & shares or innovative finance ISAs. The two limits are checked together: you can never exceed £4,000 into the LISA or £20,000 in total.
Can I pay into two cash ISAs in the same tax year?
Yes. Since 2024 you can pay into multiple ISAs of the same type within one tax year — for example two cash ISAs with different providers. The combined total across every ISA you pay into still cannot exceed £20,000, which is exactly what this calculator tracks.
Does investment growth use up my ISA allowance?
No. The allowance measures money you pay in, not what the account is worth. If your stocks & shares ISA grows in value, or your cash ISA earns interest, none of that counts against the £20,000 — only fresh contributions do. That is why long-held ISAs can be worth far more than the sum of the allowances used to build them.
Do I need to declare ISA interest or gains on a tax return?
Never. Interest, dividends and capital gains inside an ISA are tax-free forever and do not need reporting to HMRC at all — they do not appear on a Self Assessment return and do not count towards any other allowance. This is the core of the ISA deal: once money is inside the wrapper, the tax system ignores what it earns.