Your ISA Is Changing. Here Is What to Do Before April 2027.

You are under 65. You have an ISA, or you have been meaning to open one. The ISA rules are changing on 6 April 2027, and three of the changes will hit your wallet directly.

The current tax year, which runs to 5 April 2027, is the last one under the old rules. After that, things tighten. This is not something to panic about. It is something to understand and act on before April.

Here is what is changing, what it means for you, and what to do this month.

Change 1: The Cash ISA Allowance Drops From £20,000 to £12,000

The overall ISA allowance stays at £20,000. But the bit you can stick in a cash ISA, the simple savings-account bit, gets cut from £20,000 to £12,000 if you are under 65.

That is a £8,000 reduction in the tax-free space for holding cash in an ISA. If you max out the full £20,000 in a cash ISA this tax year, you have used the last full-allowance cash ISA you will ever get.

If you are 65 or older, you are exempt. The £20,000 cash ISA allowance stays with you.

Change 2: A 22% Charge on Idle Cash Inside S&S ISAs

This is the change most outlets will skip or bury in policy language. It is also the one that quietly costs people the most.

From 6 April 2027, any interest earned on cash you hold inside a stocks and shares ISA or an Innovative Finance ISA gets a flat 22% charge. That is the same rate basic-rate taxpayers pay on savings interest outside an ISA. The new rule says: if your cash is sitting inside an investment ISA, it gets treated like cash outside one.

Here is what that looks like in real numbers.

Say you keep £4,000 in cash inside your S&S ISA as a buffer. At a 4.5% easy-access rate, that generates £180 of interest in a year. From April 2027, the 22% charge takes £39.60 of that. You keep £140.40. Not dramatic on its own. But that is one example, one year, one pot.

If you have £15,000 sitting in cash across one or two S&S ISAs because you have been waiting to invest it, the charge applies to the interest on all of it. At 4.5% that is £675 of interest before the charge, £148.50 going to HMRC afterwards. You keep £526.50.

The reason this matters: the rule is designed to push people to either invest the cash or move it to a cash ISA. Leaving it idle in an investment wrapper is the worst option once the charge lands. Plain English.

Change 3: No Transfers From S&S ISA to Cash ISA for Under-65s

From 6 April 2027, if you are under 65, you cannot move money from a stocks and shares ISA back into a cash ISA.

Today you can. After April 2027, you cannot.

The direction this protects is a deliberate one. The Treasury wants cash savings parked in cash ISAs and investments held in S&S ISAs, not casual flipping between them. Whether you think that is fair or not, the rule exists and it is your rule too.

If you are 65 or older, transfers between ISA types remain unrestricted.

Who This Actually Affects

If any of these sound like you, the changes are relevant.

- You are under 65 and use a cash ISA as your main savings home.

- You have a S&S ISA with cash sitting in it, waiting to be invested or just sitting there because you forgot about it.

- You regularly top up a cash ISA and would have used more than £12,000 next tax year.

- You are between 60 and 64 and want to understand what changes when you turn 65 in the next year or two.

What To Do This Month

Three actions. None of them take more than 20 minutes.

Action 1: Decide if you want to use the full £20,000 cash ISA allowance this tax year

The 2026/27 tax year runs to 5 April 2027. If you have cash savings and want to keep them tax-free in an ISA wrapper, the full £20,000 is the most you will ever be able to put into a cash ISA again if you are under 65.

You do not have to do this. Forcing £20,000 into a cash ISA when you cannot actually afford to lock it away is worse than missing the allowance. The decision is whether your situation genuinely benefits from it.

Action 2: Check the cash balance inside your S&S ISA

Log into your S&S ISA provider. Look for the cash component. If it is over a few hundred pounds, decide one of three things before April 2027:

- Invest it into your existing funds or holdings.

- Withdraw it to your current account and then deposit into a cash ISA using this tax year's allowance (only possible before 6 April 2027).

- Leave it sitting there and accept the 22% charge on the interest from April 2027 onwards.

The first two are options now. The third is the default if you do nothing. Make it a chosen default.

Action 3: If you are 60 to 64, check whether turning 65 protects you

If you are 60 to 64 right now, you might be 65 before the changes bite. The exemptions apply by age, not by tax year. A simple check of your date of birth against 6 April 2027 tells you whether you keep the £20,000 cash ISA allowance and avoid the 22% charge.

A Real Example

A 42-year-old in Manchester with £15,000 in a S&S ISA they opened five years ago. £6,000 of it is invested in a global index fund. £9,000 has been sitting in cash inside the ISA since they meant to invest it and never did.

From April 2027, that £9,000 starts earning interest at the S&S ISA cash rate, currently around 4.0% to 4.5% at most providers. £380 of interest in a year, give or take. After the 22% charge, the ISA keeps £296.40. The difference between acting and not acting is £83.60 a year on that pot alone.

The bigger number is the £9,000 itself. If it was going to sit there indefinitely, the cash ISA option is real. If it was supposed to be invested, this is the moment to actually invest it.

That is what the new rules are pushing you towards. Either decide it is invested money and invest it, or decide it is cash savings and put it where cash savings belong.

What About Existing ISAs You Already Have

Your existing ISAs do not disappear. The wrapper stays. The growth stays tax-free inside the wrapper. The new rules only affect new contributions and idle cash interest from April 2027 onwards.

A £40,000 cash ISA you opened in 2024 keeps its tax-free status. The interest it earns keeps being tax-free. What changes is how much new money you can put into one each year.

The Bottom Line

Three rules are tightening from 6 April 2027. The cash ISA allowance halves for under-65s. Idle cash inside S&S ISAs gets a 22% charge. Transfers from S&S ISA to cash ISA are blocked for under-65s.

None of this is a reason to panic. All of it is a reason to look at where your money actually sits this week.

This tax year, ending 5 April 2027, is the last one under the current rules. Use it deliberately if it makes sense for your situation, and review your S&S ISA cash position before April so the 22% charge does not land on money you did not mean to leave there.