The cash ISA as most people know it is on borrowed time. Under draft regulations published by HMRC on 16 July 2026, anyone aged 64 or under will only be able to pay £12,000 a year into cash ISAs from 6 April 2027. The overall £20,000 ISA allowance survives, but for younger savers the remaining £8,000 will only fit inside a stocks and shares or innovative finance ISA. Savers aged 65 and over keep the full £20,000 cash allowance.

That is the headline, and it has produced a predictable mix of outrage and panic. Both are worth examining, because the details of the draft say something different from the headlines: most savers will not hit the new cap at all, the people who will are exactly the ones with the best reasons to hold cash, and there is still a full tax year to plan around it.

What do the draft rules actually say?

The proposal is a technical consultation on The Individual Savings Account (Amendment) Regulations 2026, published on 16 July and now closed. It is draft secondary legislation, which means it is not yet law: the regulations still have to be made before any of this takes effect. The policy direction was announced at Autumn Budget 2025; the July draft supplies the mechanics.

Two rows of that table matter more than the headline. The transfer ban means an under-65 cannot route around the cap by subscribing to a stocks and shares ISA and moving the money across, and it also removes a genuinely useful option: shifting invested money into cash when your circumstances change. And the proposed charge on interest earned on cash held inside investment ISAs is there to stop the obvious dodge of leaving the money uninvested. The drafters have thought about the workarounds.

Who actually hits the £12,000 cap?

Fewer people than the outrage suggests. The parliamentary petition against the change makes the point itself: the average annual cash ISA subscription is around £7,000, comfortably under the new cap. If you drip £300 a month into a cash ISA, nothing about April 2027 affects you, and your existing balances are untouched either way.

The people who do hit it are a specific group: savers moving £15,000 to £20,000 a year into cash. That describes someone building a house deposit over two or three years, someone in their fifties and sixties de-risking ahead of retirement, and anyone parking the proceeds of a house sale or inheritance while they decide what to do. Critics, including building societies, have argued this is precisely the money that should not be pushed towards investment risk, because it has a short time horizon and a fixed purpose. The age split has drawn particular fire: a 65-year-old keeps the £20,000 cash allowance while a 65th-birthday-in-May saver does not, which is hard to defend as anything but arbitrary.

The Treasury’s counterargument is that Britain holds too much long-term wealth in cash, and that £12,000 a year of new cash saving is still generous. Both things can be true. The policy is aimed at money that sits in cash for decades; the collateral damage lands on money that sits in cash for three years for a good reason.

What should savers do before April 2027?

The current tax year and the next one, 2026/27 running to 5 April 2027, are the last under the old rules if the draft goes through unchanged. That makes the planning straightforward rather than clever.

If you are a heavy cash saver, use the full £20,000 cash allowance while it exists, and remember the cap restricts new subscriptions, not balances: money already inside cash ISAs stays there, keeps its tax wrapper, and can still be transferred between cash ISAs for better rates. The rates themselves are also cooperating for now. According to Which?, the best one-year fixed cash ISA paid 4.91% in early August, with longer fixes touching 5%, and NS&I lifted its fixed bonds to between 4.82% and 4.85% on 19 August. With the Bank of England holding Bank Rate at 3.75% in July by six votes to three, and the three dissenters voting for a rise, nobody should assume today’s rates survive the winter, a dynamic we covered when we looked at why rates moved the way they did this year.

Two cautions before anyone stuffs every spare pound into cash. First, this is still a draft: consultations produce amendments, and the final regulations could soften the cap, change the age rule or slip the date. Acting on the parts that benefit you anyway, like using an allowance you were going to use, is sensible; reorganising your finances around an unmade law is not. Second, filling a cash ISA is only the right move if cash is the right home for that money. If it is a ten-year pot, the argument for investing it existed before this policy and exists after it. The same logic we applied to the two-year versus five-year fix decision applies here: match the product to your actual time horizon, not to a rule change.

Frequently asked questions

Does the £12,000 cap affect money already in my cash ISA? No. The cap applies to new subscriptions from 6 April 2027. Existing balances keep their tax-free status in full, and transfers between cash ISAs remain allowed, so you can still chase better rates on old money.

Can I put £12,000 in cash and £8,000 in stocks and shares? Yes. The overall £20,000 allowance is unchanged; only the cash portion is capped for under-65s. The draft blocks the reverse route, moving invested ISA money back into cash, for under-65s.

Is this definitely happening? Not yet. The regulations were published in draft on 16 July 2026 and the consultation has closed, but they have not been made law. The direction is clearly signalled, the details could still move.

Why are over-65s exempt? The government’s logic is that older savers legitimately need capital security. Critics call the cliff-edge arbitrary, and it is one of the most challenged features of the draft.

The cash ISA cap is that unusual thing: a policy that will genuinely affect only a minority of savers, wrapped in a headline that alarms all of them. Work out which side of the £12,000 line your actual saving habits fall on, and most of the anxiety resolves itself. If you are under it, carry on. If you are over it, you have until April 2027 and one full allowance year to arrange things on your own terms, which is more notice than savers usually get.

In the first week of September, Halifax, TSB and HSBC all trimmed fixed mortgage rates while the wholesale costs those fixes are built on went sharply the other way. Moneyfacts’ Rachel Springall said on 2 September that swap rates “have risen dramatically over the past week, reaching 30-day highs”, and that the UK 10-year gilt yield had climbed above 5.2%, its highest since 2008.

Only one of those facts can win. Moneyfacts figures for 2 September put the cheapest remortgage two-year fix at 4.55% and the cheapest homebuyer two-year fix at 4.47%, against an average two-year fix of 5.59% on 3 September. Those best buys are, for now, priced below where the market says funding costs. Here is why that happens, why it never lasts, and why panic is still the wrong response.

What are swap rates and why do they set fixed mortgage rates?

A fixed-rate mortgage is a promise to take a set rate for two or five years whatever happens in between. That is a risk for a lender funding itself at rates that move, so lenders hedge it with interest rate swaps: contracts that exchange a floating stream of interest for a fixed one over a matching term.

The price of that contract is the swap rate, in effect the market’s forecast of average short-term rates over the term. A lender prices a fix by starting from the matching swap and adding its costs, risk margin and profit, so when the swap moves the poster rate moves with it. Gilt yields, the benchmark for long-term sterling borrowing, pull in the same direction: a 10-year yield at its highest since 2008 drags swaps up because both price the same expectation of rates staying higher for longer.

Why does Bank Rate matter less to a fixed rate than most people think?

Bank Rate has sat at 3.75% since 18 December 2025 and was held again on 30 July, yet fixed-rate pricing has moved throughout. Bank Rate is a today number; a fixed rate is a next-five-years number.

Fixes follow the market’s forecast of Bank Rate, which is far more volatile than Bank Rate itself. That is why UK mortgage rates went up in August while Bank Rate did not.

The forecast has shifted because the inflation picture has. Governor Andrew Bailey said on 30 July that inflation had fallen faster than expected but that the Middle East conflict meant high and volatile energy prices. Ofgem gave that worry a number on 26 August: the price cap rises 4% to £1,723 from 1 October, on wholesale gas up 11% in three months. That is what makes investors demand a higher yield.

Why would a lender cut rates into a rising market?

Three reasons, usually together.

The first is volume. The Bank of England’s Money and Credit release on 1 September showed 56,053 mortgage approvals for house purchase in July, the lowest since January 2024 and down from a revised 58,215 in June. A weak summer leaves lending targets short, and competition for a thin pool of borrowers drove the week’s cuts: Halifax by up to 0.11 percentage points for purchase and 0.13 for remortgage, TSB by up to 0.20 points across two, three and five-year products, HSBC on two- and five-year remortgage rates.

The second is timing. A cut announced on 1 September was almost certainly agreed on August swap rates; the lender has not yet caught up.

The third is hedging. Lenders buy swaps in tranches, in advance, to cover planned lending. A tranche bought before the move is locked at the old price, so fixes can be sold against it until it runs out. The next tranche costs what swaps cost now.

What were the cheapest deals on offer this week?

The best buy sits more than a full point below the average in every column, a reminder of why the advertised mortgage rate is not the rate most borrowers are offered. The best buys also carry the thinnest margin over the swap, so they go first.

Why does the window close so quickly?

When swaps jump, the deals closest to the old funding cost turn loss-making first. A lender at 4.47% has less room than one at 5.59%, so the market leader acts first, usually by withdrawing the product at short notice before it attracts applications the lender no longer wants at that price. That is why Moneyfacts urged borrowers on 2 September to secure a new deal quickly.

None of this is a prediction: swaps rose over one week and can fall back the next. The narrower point is that a lender cutting into a rising market is spending down a hedge or chasing a target, and both run out.

Does any of this mean a borrower should rush?

Here is the case against the headline. Nobody can time swap rates, including the lenders. A borrower who grabs a two-year fix because five-year swaps look expensive, while planning to stay put for a decade, has solved a small problem by creating a large one. Early repayment charges, or refixing in two years into a market nobody can foresee, will generally cost more than a rate that moved a fifth of a point during the decision. The term is the decision; the rate is only its price. A deal ending within six months can usually be reserved now and switched if pricing improves.

The 17 September decision deserves the same treatment. Whether the MPC holds at 3.75% or not, fixes may do nothing, because the swap market has already priced in what it expects. The decision that moves trackers is not the one that moves the two-year fix.

Frequently asked questions

What is the difference between a swap rate and Bank Rate?
Bank Rate is the rate the Bank of England sets today. A swap rate is the market’s price for exchanging floating interest for fixed over a set term, so it reflects where investors expect Bank Rate to average over that term.

Why did a rise in the 10-year gilt yield affect two-year mortgage rates?
Gilt yields and swap rates price the same expectations for inflation and interest rates, so a higher-for-longer view in gilts feeds straight into the swaps lenders use to price fixes.

If lenders are still cutting, is the market really getting worse?
The cuts in the week to 1 September were agreed on earlier swap levels to win volume after weak July approvals. They describe lenders’ targets, not where funding costs are heading.

Will fixed rates fall if the Bank cuts on 17 September?
Not necessarily. If a cut is expected, the swap market has already priced it in and fixes may not move. Only trackers and variable rates follow the decision directly.

The week’s rate cuts and the week’s rise in swap rates are not a contradiction; they are a lag. Lenders are selling last month’s funding costs into a market that has moved, and the deals nearest the edge go first. Worth knowing if a fix is ending soon, but not a reason to choose the wrong term in a hurry.