ISA Allowance Explained: How Much Can You Put In Each Year?

Our Stocks and Shares ISA guide covers what the account itself is. The allowance is the other half of the picture — a yearly limit on how much you can put into ISAs in total, and it catches people out in a few predictable ways.

The allowance is per tax year, and it is shared across ISA types

Each tax year (6 April to 5 April), there is a single overall ISA allowance that applies across all your ISAs combined — Stocks and Shares, Cash, Innovative Finance, and Lifetime ISA together, not a separate allowance for each type. You can split your contributions across different ISA types within the same tax year, as long as the combined total does not exceed the overall allowance.

The Lifetime ISA has its own separate sub-limit

If you have a Lifetime ISA (aimed at first-time home buyers and retirement saving, available to those within a specific age range when opened), there is a separate, lower annual limit specifically for Lifetime ISA contributions, which counts toward, rather than sitting outside of, your overall ISA allowance.

The allowance does not carry over

Unused allowance does not roll over into the next tax year — if you do not use it, it is simply gone once the tax year ends. This is different from some other tax-efficient allowances that permit limited carry-forward, and is a common point of confusion.

What happens if you accidentally exceed it

Providers generally have checks to prevent you from paying in more than the allowance within a single ISA, but exceeding the overall allowance can still happen if you contribute to multiple ISAs across different providers without tracking the combined total. If this happens, HMRC can require the excess (and any income or gains on it) to be treated as if it were never in an ISA, which can create an unexpected tax bill — so it's worth tracking contributions carefully if you use more than one ISA provider in the same tax year.

"Flexible" ISAs and withdrawals

Some ISAs are designated "flexible," meaning you can withdraw money and pay it back in within the same tax year without it counting twice against your allowance. Not all ISAs are flexible — check with your specific provider before assuming a withdrawal and later top-up won't affect your allowance.

Why using the allowance each year (if you can) is generally worthwhile

Because the allowance does not carry forward, many people treat "use what you can of this year's allowance" as a standing habit rather than an occasional decision, since an unused allowance represents a permanently lost opportunity to shelter that year's investment growth from tax, not something that can be made up for later.

This is general education, not personalised financial advice. Investing involves risk, including the risk of losing money, and past performance is not a guide to future returns. Nothing here recommends any specific investment — for anything genuinely complex or high-stakes, speak to a regulated financial adviser.