The 2025 Autumn Budget brought important changes to ISAs, due to take effect from 6 April 2027. For savers under 65, the Cash ISA allowance is being cut from £20,000 to £12,000. The headline £20,000 total ISA allowance is unchanged, but the remaining £8,000 has to be invested rather than held as cash.
Even though the changes aren't here yet, the next tax year is a useful moment to think about whether your current ISA strategy still fits.
What changes on 6 April 2027
The new rules take effect from the start of the 2027-28 tax year:
| ISA type | Allowance for under-65s (current) | Allowance for under-65s (from April 2027) |
|---|---|---|
| Cash ISA | Up to £20,000 | Up to £12,000 |
| Stocks and Shares ISA | Up to £20,000 | Up to £20,000 |
| Innovative Finance ISA | Up to £20,000 | Up to £20,000 |
| Lifetime ISA (under-40s) | Up to £4,000 | Up to £4,000 |
| Total annual ISA allowance | £20,000 | £20,000 |
For savers aged 65 and over, nothing changes. The full £20,000 can still be held in a Cash ISA.
The Government's stated rationale is to encourage more UK savers to invest rather than hold cash. With Cash ISA rates having drifted lower as the Bank of England cut its base rate, and Stocks and Shares ISAs significantly outperforming cash over recent years, the policy aim is to nudge more long-term saving towards investments.
What changes for higher earners and households with significant cash
For most UK savers, the £12,000 Cash ISA limit will be more than enough. Median household savings sit well below that figure. But for households with substantial cash balances, perhaps because of an inheritance, a property sale, a redundancy payment or a business exit, the change may have a real impact.
Higher earners and households with significant emergency reserves often hold £30,000-£100,000 in cash. Today that can build up tax-efficiently across multiple tax years using full Cash ISA allowances. From April 2027, that path narrows.
Practical implications:
- The 2025-26 and 2026-27 tax years are the last full opportunities to maximise Cash ISA contributions before the cap drops
- For longer-term cash that doesn't need to be liquid, the shift towards Stocks and Shares ISAs is the natural alternative, but only suits money you can leave invested for at least 5-10 years
- For cash that does need to be liquid (emergency funds, short-term goals), Premium Bonds, high-interest savings accounts and easy-access savings outside the ISA wrapper become more important
Cash ISAs vs Stocks and Shares ISAs: when each makes sense
The simplest way to think about it: cash protects your money, investing grows it.
Cash ISAs are well suited to:
- Emergency funds (typically 3-6 months of essential outgoings)
- Short-term savings goals (under 5 years)
- Money you might need quickly
- Savers who don't have the capacity or appetite for capital at risk
Stocks and Shares ISAs are well suited to:
- Long-term goals (10+ years)
- Money that doesn't need to be accessed soon
- Savers comfortable with the value going up and down in the short term
- Building wealth that beats inflation over time
According to Moneyfacts, the average Stocks and Shares ISA returned 11.22% between February 2025 and February 2026, compared to 3.48% for the average Cash ISA. This was the third consecutive year that investing outperformed cash. Over longer periods, the gap typically widens.
There is no guarantee that investing will outperform cash in any given year. The value of investments, and any income from them, can go down as well as up, and you could get back less than you invested.
A practical framework for thinking about your ISA strategy
For most UK savers, a workable approach is to split ISA contributions across three time horizons:
- Cash for the short term. The first portion goes to Cash ISA, emergency fund plus anything you might spend within five years.
- Investments for the long term. The remainder goes to Stocks and Shares ISA, where it sits for at least 10 years.
- Lifetime ISA for under-40s saving for a first home or retirement. If applicable, up to £4,000 of the annual allowance gets a 25% government bonus.
The right split depends entirely on personal circumstances. For someone with substantial existing cash and a long working life ahead, the Stocks and Shares share might be most of the £20,000. For someone close to retirement or in a less certain financial position, the cash share might be larger.
What to do this tax year
A few practical steps worth considering:
- Use the 2026-27 allowance. The £20,000 allowance doesn't carry over. If you don't use it by 5 April 2027, you lose it.
- If you have meaningful cash savings outside an ISA, this is the last full year to move up to £20,000 into a Cash ISA before the limit drops.
- If you've been a Cash-ISA-only saver, this is a sensible moment to learn how Stocks and Shares ISAs actually work, even before opening one.
- Review existing ISAs. Older Cash ISAs may be paying very low rates. Transferring an ISA from one provider to another preserves the tax wrapper.
- Consider regular monthly contributions rather than a lump sum at the end of the tax year. Monthly contributions reduce the risk of investing all your money on a bad day.
Where this fits with the rest of your finances
ISAs don't sit in isolation. They sit alongside pensions, GIAs, cash savings and longer-term planning. For UK savers, the rough order of priority is usually:
- Build an emergency fund (Cash ISA or easy-access savings)
- Maximise employer pension matching (free money)
- Pay down high-interest debt
- Maximise ISA contributions for tax-efficient growth
- Top up personal pension for additional tax relief
- Consider GIAs for any surplus
If you're at the start of your investing journey, our guide to how to start investing in the UK covers the building blocks. If you're closer to retirement and your ISAs sit alongside meaningful pension wealth, our article on why your pension needs regular reviews is the right complement.
Frequently asked questions
What is the UK ISA allowance for 2026?
The total ISA allowance for the 2026-27 tax year is £20,000 per UK adult. This can be split across a Cash ISA, Stocks and Shares ISA, Innovative Finance ISA and Lifetime ISA (capped at £4,000). The Junior ISA allowance is £9,000 per child.
How are UK ISAs changing from April 2027?
From 6 April 2027, the Cash ISA allowance for UK savers under 65 reduces from £20,000 to £12,000 per tax year. The total ISA allowance remains £20,000, with the remaining £8,000 needing to be held in a Stocks and Shares ISA, Innovative Finance ISA or Lifetime ISA. Savers aged 65 and over can still use the full £20,000 in cash.
Should I switch from a Cash ISA to a Stocks and Shares ISA?
It depends on your time horizon and risk tolerance. The average Stocks and Shares ISA returned 11.22% in the year to February 2026 against 3.48% for the average Cash ISA, according to Moneyfacts. However, Stocks and Shares ISAs carry capital risk, and money you might need within five years is usually better held in cash. A common approach is to hold an emergency fund and short-term savings in cash, and invest longer-term money through a Stocks and Shares ISA.
Can I have a Cash ISA and a Stocks and Shares ISA in the same year?
Yes. From 6 April 2024, you can pay into multiple ISAs of the same type or different types in the same tax year, as long as your total contributions across all ISAs stay within the £20,000 annual allowance. For the 2026-27 tax year, you could open a new Cash ISA and a new Stocks and Shares ISA and split your £20,000 between them however you choose, subject to provider minimums.
What's the difference between a Cash ISA and a Stocks and Shares ISA?
A Cash ISA holds your money as cash, earning interest. Your capital is protected (subject to the FSCS £85,000 limit per banking institution) but returns may not keep up with inflation. A Stocks and Shares ISA invests your money in shares, bonds or funds. Returns are not guaranteed and the value can fall, but historically Stocks and Shares ISAs have outperformed Cash ISAs over the long term. Both grow free of UK income tax and capital gains tax.
Sources: GOV.UK, Tax-Free Savings Newsletter; Moneyfacts, Investing vs Cash ISAs; MoneyHelper, Stocks and Shares ISAs; HM Treasury Autumn Budget 2025.