Open a banking app this week and you'll spot the same thing on Monzo, Chase and Trading 212: a Cash ISA tile sitting right next to your current account, paying a rate that would have looked absurd three years ago. The £20,000 allowance resets every 6 April, the new tax year is barely twelve weeks old, and the question half of Britain is quietly asking is whether the tax-free wrapper is still worth bothering with — or whether the speculation about Rachel Reeves slashing the allowance means you should pile in now while you can.
Here's the short version before the detail: if you pay tax on your savings interest, a Cash ISA is almost always worth it in 2026. The longer version is where it gets interesting, because the gap between what the high-street giants pay and what the app-based challengers pay has become embarrassing — and the rules around moving money between providers are not what most people assume.
What the Cash ISA actually does for you in 2026
A Cash ISA shelters the interest your savings earn from income tax. That sounds dull until you remember the Personal Savings Allowance, which lets a basic-rate taxpayer earn £1,000 of interest tax-free outside an ISA, and a higher-rate taxpayer just £500. Additional-rate taxpayers — anyone earning above £125,140 — get nothing at all. With easy-access rates sitting around 4% to 4.5% across much of the market, a basic-rate saver now breaches that £1,000 threshold with roughly £22,000 in an ordinary savings account. Above that line, every extra pound of interest is taxed at 20%, 40% or 45%.
This is the bit that has changed the maths. For most of the 2010s, savings rates were so low that the Personal Savings Allowance covered almost everyone, and the Cash ISA looked like a relic. Rates climbed, the allowance stayed frozen at £1,000, and suddenly millions of ordinary savers — not just the wealthy — found themselves with a tax bill on their interest for the first time. HMRC collects this automatically through your tax code in many cases, which means people are paying it without ever filling in a form, and often without realising. The Cash ISA quietly became relevant again, and the providers noticed.
The allowance is £20,000 per person per tax year, and it covers all your ISAs combined — Cash, Stocks and Shares, Innovative Finance and the Lifetime ISA all draw from the same £20,000. A couple therefore shelters £40,000 a year between them. You don't get a separate allowance for each type, which is the single most common misunderstanding I hear, usually from someone who has just discovered they've over-subscribed across two providers.
The high street versus the apps: a genuinely uncomfortable gap
Walk into a branch and the loyalty Cash ISAs from the big four still pay rates that border on insulting — some variable easy-access ISAs from the largest banks have at points paid well under 2%, while the same bank advertises a headline savings account at more than double that. The assumption baked into those products is that you won't move. Most people don't. That inertia is worth billions to them.
The app-based challengers built their entire pitch on the opposite bet. Chase, Monzo, Trading 212 and the savings marketplaces such as Raisin UK have spent the last two years competing hard on Cash ISA rates, often landing near the top of the easy-access tables. Trading 212 in particular made noise with a flexible Cash ISA that pays daily interest, while Monzo folds its ISA into the same app where you already see your spending. None of this is charity — they want your deposit base — but the practical result is that a saver who moves from a high-street loyalty ISA to a top app rate can pick up a meaningful chunk of extra interest for an afternoon's admin.
A word of caution that the comparison sites tend to bury: some of the very best advertised rates are bonus rates that drop off after twelve months, and a few of the headline "5%" deals over the past couple of years have been regular-saver structures that cap how much you can pay in each month. Read whether the rate is fixed, variable, or variable-with-a-bonus before you move. A flat 4.3% that stays put can beat a 4.8% that collapses to 2.5% in March.
Flexible ISAs, and the trick most people miss
Not every Cash ISA is a "flexible" ISA, and the distinction is worth real money. A flexible Cash ISA lets you withdraw money and pay it back in the same tax year without it counting twice against your £20,000 allowance. Say you've put in the full £20,000, then take out £5,000 in November for a boiler repair — with a flexible ISA you can return that £5,000 before 5 April and still be within your allowance. With a non-flexible ISA, that £5,000 is simply gone from this year's allowance; pay it back and you've over-subscribed.
Trading 212 and a handful of others make a point of offering flexibility; plenty of high-street ISAs do not. If you're someone whose savings genuinely move in and out — an emergency fund you dip into, a house deposit you might deploy at short notice — flexibility is not a nice-to-have, it's the feature that decides which provider you pick.
Moving an existing ISA without losing the tax shelter
This is where people make expensive mistakes. If you have £30,000 built up in a Cash ISA from previous years and you want a better rate, you do not withdraw it and re-deposit it into a new ISA. The moment that money leaves the ISA wrapper, it loses its tax-free status, and paying it back counts against this year's £20,000 allowance — so most of it simply can't go back in.
The correct route is an ISA transfer. You open the new ISA and ask the new provider to pull the money across directly from the old one. The cash never touches your hands, the tax shelter is preserved, and money from previous tax years doesn't eat into this year's allowance. Cash ISA transfers are supposed to complete within 15 working days under the industry rules. The catch worth flagging: a minority of older fixed-rate ISAs charge an exit penalty of 90 to 180 days' interest if you transfer before maturity, so check the terms on the account you're leaving before you start.
- Open the new ISA first, then request the transfer through the new provider — never close the old one yourself.
- Choose "transfer in" on the application, and provide the old account details so they can chase it.
- Decide whether to move previous-year money, current-year money, or both — current-year subscriptions must move as a whole.
- Watch for fixed-rate exit penalties, which can wipe out months of interest if you jump early.
Is your money actually safe? FSCS and the app question
Every Cash ISA from a UK-authorised bank or building society is covered by the Financial Services Compensation Scheme up to £85,000 per person, per banking licence. That last phrase matters more than the number. Several app brands and savings marketplaces sit on top of a partner bank's licence, which means your £85,000 protection is shared across every account you hold under that one licence — not per app, per brand, or per logo.
Chase, for instance, operates under J.P. Morgan's UK banking licence; if you held savings there and also held money with another brand sitting on the same licence, the £85,000 would cover both combined, not each separately. With Raisin UK and similar marketplaces, your money sits with the underlying partner bank you chose, and the FSCS cover follows that bank — so two products bought through the same marketplace but held with different partner banks each get their own £85,000. It's fiddly, and it's exactly the kind of detail nobody checks until something goes wrong. If you're holding more than £85,000 in cash savings, spreading it across genuinely separate banking licences is the only thing that fully protects all of it.
So should you act now, or wait?
The reform chatter is real. Through the spring of 2026 there was sustained speculation that the Treasury might cut the Cash ISA allowance to nudge savers towards Stocks and Shares ISAs and, by extension, into UK-listed companies. Whatever lands in a future Budget, one principle holds: ISA allowances have historically been use-it-or-lose-it, and money already inside the wrapper has always been left alone when the rules change. If you have cash earning taxable interest and you haven't used this year's allowance, the case for filling a Cash ISA now — rather than gambling on the rules staying generous — is straightforward.
My honest take: if you're a taxpayer breaching your Personal Savings Allowance, move a chunk into a top-paying flexible Cash ISA from one of the app challengers this month, transfer any old ISAs across rather than withdrawing them, and keep each banking licence under £85,000. The boring high-street loyalty ISA paying 1.8% is the one product in this whole market with no defence left.