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ISA & Tax WrappersISA2026/27 Tax Year

ISA Allowance Calculator

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Disclaimer: Tax and take-home pay estimates are based on published 2026/27 UK, Scottish and Welsh statutory rates and allowances. This is not tax advice, but an annual mathematical model. For personal tax planning or complex affairs, consult HMRC or a qualified tax adviser.

Tracking your ISA allowance across accounts

The £20,000 allowance is shared across every ISA you subscribe to in the same tax year. It is the total that counts, not the number of accounts.

Figures stated for the 2026/27 UK tax year. Content last checked against official sources on .

What this calculator does

  • Adds up subscriptions across cash, stocks and shares, innovative finance and Lifetime ISAs.
  • Compares the total against the £20,000 annual limit.
  • Reports the allowance still available before the tax year ends.

How the calculation works

There is no arithmetic subtlety here — the value is in the aggregation. The overall ISA subscription limit is £20,000 for the tax year, and it applies to the sum of what you put into every type of ISA, not separately to each one. The Lifetime ISA has its own lower sub-limit of £4,000, and crucially that £4,000 counts towards the overall £20,000 rather than sitting on top of it, which is the single most commonly misunderstood part of the rules. So someone paying the maximum £4,000 into a Lifetime ISA has £16,000 left for everything else, not £20,000. Because subscriptions are frequently spread across providers, and because the allowance resets on 6 April with no carry-forward, keeping a running total is the practical problem this calculator solves.

The rule

Total subscribed = cash + stocks and shares + innovative finance + Lifetime ISA. Remaining = £20,000 − total subscribed.

Step by step

  1. Add together everything subscribed to each ISA type in the current tax year.
  2. Check the Lifetime ISA element against its own £4,000 sub-limit.
  3. Subtract the total from the £20,000 overall allowance.

Worked example

Someone has paid £3,000 into a cash ISA, £12,000 into a stocks and shares ISA and £4,000 into a Lifetime ISA this tax year.

What was entered

Inputs used in the worked example
Cash ISA contributions this tax year£3,000
Stocks & Shares ISA contributions£12,000
Innovative Finance ISA contributions£0
Lifetime ISA contributions£4,000

The arithmetic

  1. Total subscriptions are £3,000 + £12,000 + £0 + £4,000 = £19,000.
  2. The Lifetime ISA element is exactly at its £4,000 sub-limit, so it will attract the maximum £1,000 government bonus.
  3. That £4,000 counts towards the overall £20,000 — it is not additional to it.
  4. £1,000 of allowance remains for the rest of the tax year.
  5. Any part of that £1,000 not used by 5 April is lost, with no carry-forward.

What the calculator returns

Results produced by the worked example
Total subscribed this tax year£19,000.00
Allowance remaining£1,000.00

Key assumptions

  • All figures are subscriptions made in the current tax year.
  • The overall limit is £20,000 and the Lifetime ISA sub-limit is £4,000.

Limitations

  • Transfers of ISA money from previous years do not count as new subscriptions and should not be entered here.
  • Junior ISAs have a separate allowance in the child's name and are outside this calculation.
  • The calculator does not check eligibility for a Lifetime ISA, which depends on your age.
  • Rules on subscribing to more than one ISA of the same type in a tax year have changed over time; check the current position on GOV.UK.
  • Withdrawing and replacing money is only allowed without using fresh allowance in a flexible ISA, and not all providers offer one.

Common questions

Does the Lifetime ISA £4,000 come out of the £20,000?
Yes, and this is the most commonly misunderstood ISA rule. Paying the full £4,000 into a Lifetime ISA leaves £16,000 for all other ISA types, not £20,000.
Do transfers use up my allowance?
No. Moving existing ISA money between providers or between ISA types is a transfer, not a new subscription, provided you use the formal transfer process rather than withdrawing and re-paying it yourself.
What happens if I go over £20,000?
The excess is not entitled to ISA treatment. HMRC will normally identify it after the tax year and instruct the provider to remove the excess subscription along with any income on it, so it is worth tracking as you go.
Is the Lifetime ISA bonus worth the restrictions?
The 25% bonus is substantial, but the money is only accessible without charge for a first home costing £450,000 or less, from age 60, or on terminal illness. Other withdrawals carry a 25% charge, which removes more than the bonus added.

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Official sources

Every figure in this guide was checked against the sources below. Where a source could not confirm a figure, it is marked as requiring verification rather than presented as settled.

  • Individual Savings Accounts (ISAs) — GOV.UK (2026 to 2027 tax year)Overall ISA subscription limit £20,000, shared across cash, stocks and shares, innovative finance and Lifetime ISAs
  • Lifetime ISA — GOV.UK£4,000 annual limit counting towards the overall ISA allowance; 25% government bonus capped at £1,000 a year; account opened before 40, contributions until 50
  • Withdrawing money from your Lifetime ISA — GOV.UKCharge-free withdrawal for a first home costing £450,000 or less, from age 60, or on terminal illness; 25% charge otherwise