UK ISA Allowance Calculator 2026/27 (£20,000 Limit)

This calculator covers the UK Individual Savings Account (ISA) allowance for the 2025/26 and 2026/27 tax years, a UK-wide (not England-only) tax-free savings and investment wrapper administered by HMRC. Every UK resident aged 18 or over (16+ for a Cash ISA) gets an annual allowance -- £20,000 for 2026/27, unchanged from the previous several tax years -- that can be split across up to four types of ISA in any combination: Cash ISA, Stocks & Shares ISA, Innovative Finance ISA (peer-to-peer lending), and Lifetime ISA (LISA). All growth, interest, and dividends inside any ISA are entirely free of both Income Tax and Capital Gains Tax.

The Lifetime ISA is the one type with its own extra rule: it has a £4,000 annual sub-limit that counts inside, not on top of, the overall £20,000 allowance, and it comes with a 25% government bonus -- worth up to £1,000 a year on a full £4,000 contribution -- provided the money is eventually used to buy a first home (up to a certain property price cap) or withdrawn from age 60 for retirement. Accounts must be opened between ages 18 and 39, but contributions (and the bonus) continue until age 50.

One imminent change worth knowing about even though it doesn't affect the year modeled here: the Autumn Budget 2025 announced that from 6 April 2027, the amount under-65s can put into a Cash ISA specifically will be cut to £12,000 a year, with any unused headroom pushed toward Stocks & Shares ISAs instead. For the whole of the 2026/27 tax year this calculator covers, the full £20,000 remains freely allocable across any combination of ISA types, with no cash-specific sub-cap yet in force.

1. Sum every ISA subscription for the tax year -- Cash, Stocks & Shares, Lifetime, and Innovative Finance -- into a single total.
2. Compare the total against the £20,000 overall allowance. Anything at or below £20,000 is a valid set of subscriptions; anything above breaches the overall limit (in practice, ISA providers and HMRC systems are designed to prevent this, but it can still happen across multiple providers who cannot see each other's records in real time).
3. Cap the Lifetime ISA portion at its own £4,000 sub-limit for the bonus calculation, separately from the overall cap -- a LISA contribution above £4,000 in a tax year is not a valid subscription for the excess amount, regardless of how much headroom remains in the overall £20,000.
4. Calculate the 25% government bonus on whichever is lower: the actual Lifetime ISA contribution, or the £4,000 sub-limit -- so the maximum possible bonus is £1,000 per tax year.

Split: £8,000 Cash ISA + £8,000 Stocks & Shares ISA + £4,000 Lifetime ISA

• Total subscribed: £8,000 + £8,000 + £4,000 = £20,000 -- uses the entire overall allowance
• Remaining allowance: £0
• Lifetime ISA bonus: £4,000 × 25% = £1,000
• Total working for the saver this year: £20,000 saved + £1,000 bonus = £21,000

Maximum LISA + remaining allowance in cash: £16,000 Cash ISA + £4,000 Lifetime ISA

• Total subscribed: £20,000, again using the full allowance
• Lifetime ISA bonus: still £1,000 (based on the £4,000 LISA contribution, unaffected by how the rest of the allowance is allocated)

Over the limit: £15,000 Cash ISA + £7,000 Stocks & Shares ISA

• Total subscribed: £22,000, which exceeds the £20,000 overall allowance by £2,000
• This is not a valid combination of subscriptions; the saver (or their providers) would need to reduce contributions to stay within £20,000 for the tax year

LISA contribution above its own sub-limit: £6,000 into a Lifetime ISA alone

• Only £4,000 counts as a valid LISA subscription and earns the bonus
• Bonus: £4,000 × 25% = £1,000 -- the extra £2,000 is not entitled to any bonus and, depending on the provider, may not be accepted as a valid LISA contribution at all

• Junior ISAs (JISAs), a completely separate allowance (£9,000 for 2025/26 and 2026/27) for under-18s, held in the child's name and not shared with the adult ISA allowance modeled here.
• The Lifetime ISA withdrawal penalty. Withdrawing LISA funds for anything other than a first home purchase, terminal illness, or from age 60 triggers a 25% government withdrawal charge -- which claws back not just the bonus but a slice of the saver's own original contribution too. Not modeled here since this calculator focuses on the contribution and bonus mechanics.
• The Lifetime ISA first-home price cap (currently £450,000), above which the bonus cannot be used toward a property purchase.
• The 6 April 2027 Cash ISA cut to £12,000 for under-65s, which does not apply to the 2026/27 tax year this calculator models.
• Flexible ISA rules, which let some providers allow withdrawals and same-year replacement without it counting against the annual allowance a second time -- not all providers offer this, and this calculator assumes a standard, non-flexible subscription pattern.
• ISA transfers between providers, which do not use up any of the annual allowance (only new money subscribed in the current tax year counts).

• Thinking the Lifetime ISA £4,000 is in addition to the £20,000. It is not -- every pound in a LISA also counts against the overall allowance, so a full £4,000 LISA contribution leaves only £16,000 for everything else.
• Missing the age cut-offs. A Lifetime ISA can only be opened between ages 18 and 39; someone who turns 40 without ever opening one permanently loses access to the bonus, even though they could still contribute to an existing LISA until age 50.
• Withdrawing LISA funds for the wrong purpose. The 25% government withdrawal charge on non-qualifying withdrawals is calculated to claw back more than just the bonus -- a saver who deposits £4,000, gets a £1,000 bonus, then withdraws early for an unrelated reason can end up with less than their original £4,000 after the charge.
• Assuming all four ISA types must be used every year. There is no requirement to spread contributions; putting the entire £20,000 into a single Stocks & Shares ISA, for example, is equally valid.
• Not accounting for multiple providers when checking the overall limit. Because different ISA providers don't always see each other's contribution records in real time, it is the saver's own responsibility to track total subscriptions across all providers and stay within £20,000.

• GOV.UK: "Individual Savings Accounts (ISAs)" -- gov.uk/individual-savings-accounts
• GOV.UK: "Lifetime ISA" -- gov.uk/lifetime-isa
• HM Treasury, Autumn Budget 2025 (26 November 2025): announcement of the Cash ISA allowance cut to £12,000 for under-65s, effective 6 April 2027.
• GOV.UK: "Junior Individual Savings Accounts (JISAs)" -- gov.uk/junior-individual-savings-accounts.