Key takeaways
- In the 2026 to 2027 tax year a higher-rate taxpayer pays 40% on bond interest and 35.75% on dividends. That gap is 4.25 points, not the 17 points American writers work with.
- The iShares Core UK Gilts ETF distributed 4.47% over the 12 months to 6 August 2026. At 40% that's 1.79% of the holding gone in tax every year.
- Its FTSE 100 stablemate distributed 2.88%. At the 35.75% upper dividend rate that's a drag of 1.03% a year — 0.76 points less than the gilt fund.
- Gilts have been exempt from capital gains tax since 2 July 1986. A gilt fund's units are not exempt, so bonds are not one asset class for this question.
- A higher-rate taxpayer's £500 personal savings allowance covers about £11,186 of that gilt fund. Below that holding size, sheltering it saves nothing.
Same £1,000 of return, four different tax bills
You've got a £20,000 ISA allowance, maybe a pension, and a general investment account holding whatever wouldn't fit. Which fund goes where?
Here's the arithmetic, for a higher-rate taxpayer in the 2026 to 2027 tax year. On £1,000 of bond fund interest you pay £400. On £1,000 of dividends you pay £357.50. On £1,000 of capital gain on shares, above the £3,000 annual exempt amount, you pay £240. On £1,000 of capital gain on a gilt you own directly, you pay nothing. Inside an ISA, every one of those is zero.
The chart above sets those bars side by side. That ranking is the whole of asset location, and the interesting part is how close the top two are.
Interest is taxed at 40% and dividends at 35.75% — a gap of 4.25 points
Savings interest has no special rate. GOV.UK puts it plainly: "You pay tax on any interest over your allowance at your usual rate of Income Tax." For 2026 to 2027 those rates are 20% on the basic rate band, 40% on the higher rate band and 45% above it.
Dividends run on their own scale. The ordinary rate is 10.75%, the upper rate 35.75% and the additional rate 39.35%, with a dividend allowance of £500. The first two rose on 6 April 2026, which narrowed the gap this whole question turns on. The order in which UK income is taxed decides which of those rates you actually face.
So for a higher-rate taxpayer the gap between interest and dividends is 4.25 points. For an additional-rate taxpayer it's 5.65 points. That is the entire tax case for putting one asset in the shelter ahead of the other, before capital gains enter it.
Put the yields in and the gilt fund still loses by 0.76 points a year
Rates alone don't measure drag. What matters is the rate multiplied by how much taxable income the asset actually throws off.
Take two funds from the same manager, each with a 0.07% total expense ratio. The iShares Core UK Gilts UCITS ETF (IGLT) showed a 12-month trailing distribution yield of 4.47% as of 6 August 2026. The iShares FTSE 100 UCITS ETF (ISF) showed 2.88% on the same date.
Outside a wrapper, a higher-rate taxpayer sees the gilt fund's 4.47% taxed at 40%. That's 1.79% of the holding, every year. The equity fund's 2.88% is taxed at 35.75%, which is 1.03%. The gilt fund costs 0.76 percentage points a year more, on income alone.
Scale it to the ISA allowance. £20,000 in the gilt fund produces £894 of interest and a £357.60 tax bill. The same £20,000 in the FTSE 100 fund produces £576 of dividends and £205.92 of tax. Sheltering the gilt fund is worth £151.68 a year more, if your allowances are already spoken for elsewhere.
That's the textbook answer, and on these two funds it holds. Then it stops holding.
Gilts are exempt from capital gains tax and a gilt fund is not
HMRC's Capital Gains Manual is unambiguous: "Since 2 July 1986 all disposals of gilt-edged securities have been exempt from Capital Gains Tax." GOV.UK's list of what capital gains tax doesn't touch names "UK government gilts and Premium Bonds" alongside ISAs.
The exemption belongs to the gilt, not to a fund that holds gilts. Units in a gilt fund are an ordinary chargeable asset, taxed at 18% or 24%. The cash such a fund pays out is taxed as interest rather than as a dividend, because of a 60% test. An authorised fund can only make an interest distribution where "the market value of its qualifying investments exceeds 60% of all its investments". The offshore rule works the same way: where a fund holds more than 60% of assets in interest-bearing form, "any distribution or excess of reported income is treated as a payment of yearly interest".
Now hold the gilt directly. GOV.UK's own list of gilts exempt from capital gains tax includes 0⅛% Treasury Gilt 2028. Its coupon is 0.125% a year. On £10,000 nominal that's £12.50 of taxable interest and £5.00 of tax at 40%. Everything else the holding earns — the pull from a discounted price back up to par — is capital, and exempt.
Set that against £10,000 in the gilt fund: £447 of interest and £178.80 of tax. Same borrower, same credit risk, 35.8 times the tax bill. The fund isn't doing anything wrong. It holds gilts with a weighted average coupon of 3.04%, so most of what it earns arrives as taxable income rather than as exempt capital.
This is where the imported rule of thumb breaks. In the United States no asset turns bond return into an exempt gain. In the UK one does, and it's the most ordinary bond a person can buy.
The "bonds in the tax shelter" rule comes from a 17-point American gap
The rule was written for a different tax code. In the US, interest is ordinary income, and for tax year 2026 "the top tax rate remains 37% for individual single taxpayers with incomes greater than $640,600". Long-term gains and qualified dividends sit on a separate scale. For taxable years beginning in 2025 the IRS says "the tax rate on most net capital gain is no higher than 15% for most individuals", rising to 20% above the top threshold.
So an American deciding what to put in a retirement account faces a spread of roughly 17 points between interest and equity income. A British higher-rate taxpayer faces 4.25. Same rule of thumb, a quarter of the force behind it.
The UK gap does widen from April 2027. The savings basic rate goes to 22%, the savings higher rate to 42% and the savings additional rate to 47%, while dividend rates stay where they are. A higher-rate taxpayer's interest-versus-dividend gap becomes 6.25 points. Still not 17.
An accumulating offshore fund taxes you on cash you never see
There's a worse case than a gilt fund in a taxable account, and it's an accumulating one. A reporting offshore fund has to tell UK investors what it earned, not just what it handed over. HMRC's helpsheet defines the difference: "The difference per unit between your reportable income and the income that is distributed to you is known as 'excess reported income'."
You're taxed on it whether or not it reaches your bank account. HMRC treats it as received on a fund distribution date that falls 6 months after the reporting period ends. It also keeps the character of the underlying income. If the fund is a bond fund, that excess is taxed as interest — 40% for a higher-rate taxpayer, on money that never left the fund. Accumulation units and excess reportable income works it through on a real fund report.
Inside an ISA none of that exists. GOV.UK is blunt about it: "If you complete a tax return, you do not need to declare any ISA interest, income or capital gains on it."
Below about £11,186 in that gilt fund, location changes nothing
Allowances come first, and for smaller holdings they make the whole question moot.
The personal savings allowance is £1,000 at the basic rate, £500 at the higher rate and £0 at the additional rate. The dividend allowance is £500 for everybody. There's also a starting rate for savings of up to £5,000, which disappears once your other income reaches £17,570.
Run the yields through those. At 4.47%, a higher-rate taxpayer's £500 covers about £11,186 of the gilt fund, and a basic-rate taxpayer's £1,000 covers about £22,371. At 2.88%, the £500 dividend allowance covers about £17,361 of the FTSE 100 fund. Under those sizes the ISA saves nothing on income — though it still shelters gains, and keeps sheltering them as the holding grows.
An additional-rate taxpayer has no personal savings allowance at all, so their first pound of interest is taxed at 45%. Where each allowance sits matters as much as how big it is, and the full 2026 to 2027 rates and allowances table lays that ordering out.
A pension shelters the growth and taxes the exit
A pension isn't a larger ISA. Two things are true at once, and they pull in opposite directions.
Inside the scheme, tax stops. HMRC's Pensions Tax Manual: "income derived from investments or deposits held for the purposes of a registered pension scheme is exempt from income tax", and gains on disposal of scheme investments "are exempt from capital gains tax". On investment return, a pension and an ISA do the same job.
On the way out they part company. "PAYE applies to all pensions paid from registered pension schemes." A quarter can normally come out free of tax — the applicable amount "represents 25% of the capital value of the benefits coming into payment" — subject to a lump sum allowance of £268,275. The rest is taxed as income.
Which is why a pension's value tracks the tax rate of the money going in, far more than the asset going in. Relief arrives at your marginal rate: a higher-rate taxpayer claims "20% up to the amount of any income you have paid 40% tax on", on contributions of up to 100% of earnings and inside a £60,000 annual allowance. The shelter is worth most where income is taxed at 40% or 45% now and 20% later. That's a fact about your income, not about whether you hold gilts or equities.
The strongest case against sorting by asset at all
Three objections, and they're good ones.
First, the sums are small in absolute terms. 0.76 percentage points on a £20,000 holding is £151.68 a year. A platform fee difference can be larger, and it's certain rather than contingent on a yield that moves.
Second, the yields are a snapshot. 4.47% and 2.88% are 12-month trailing figures at 6 August 2026. Gilt yields spent much of the 2010s near zero, and at a 1% distribution yield the same 40% rate costs 0.40% a year. The ranking survives that; the size of the prize doesn't.
Third — and this is the objection that bites — location constrains rebalancing. Put every bond in the ISA and every equity outside it, and each rebalance outside the wrapper becomes a disposal, matched under HMRC's share matching rules and taxable above the £3,000 exempt amount. A tidy tax position can produce an untidy portfolio, and the portfolio is the thing that determines the return.
What this arithmetic cannot tell you
It's arithmetic about two funds on one day. 4.47% and 2.88% are trailing distribution yields as of 6 August 2026, not forecasts, and a payout can move a long way in a year. The gilt fund's 4.80% weighted average yield to maturity is a better guide to its future return than its trailing distribution, and those aren't the same number.
Every rate here belongs to 2026 to 2027, and UK rates have moved twice in short order. Dividend rates rose on 6 April 2026 and savings rates rise again in April 2027. A location decision made on today's spread is a bet that the spread persists, and the recent record argues against that.
The arithmetic also ignores everything that isn't tax on UK income. Withholding tax on foreign dividends, platform charges, whether a holding is even available inside a given wrapper, and what happens to an ISA on transfer or on death all move the answer, and none of them show up in a rate table.
It says nothing about the size of your accounts either. If everything fits inside the ISA, there is no location decision to make. The question only exists at the margin, where one more pound has to sit somewhere taxable.
What would change the conclusion
If the dividend and savings scales converged, the case for sorting by asset type would go with them. They're moving apart rather than together: from April 2027 the savings higher rate is 42% against a 35.75% dividend upper rate, a spread of 6.25 points.
If you hold gilts directly instead of through a fund, the ranking inverts. A low-coupon gilt outside a wrapper is taxed on 0.125% of nominal and exempt on the rest, which makes it one of the most tax-efficient assets a UK investor can hold in a taxable account. Spending ISA allowance on it buys shelter from a tax that isn't being charged.
And if your income is high enough that the personal savings allowance is £0 and relief runs at 45%, the account arithmetic swamps the asset arithmetic. The question stops being which asset and becomes which wrapper — which is a question about your marginal rate this year and your expected marginal rate in retirement.
The number worth watching isn't a headline rate. It's how much of your taxable holdings' return arrives as income you can't defer, because that's the part location can still change, and the part no rate table shows you.