On 13 July 2026, while the FTSE 100 traded above 10,700 and closed at yet another record high, HMRC published a policy paper that will do more to the price of your next share purchase than any single day's market move. The document, titled Modernisation of the Stamp Taxes on Shares framework, sets out plans to scrap two of the oldest taxes in British finance — Stamp Duty and Stamp Duty Reserve Tax — and replace them with a single Securities Transfer Tax. If you hold shares through a Stocks and Shares ISA, a SIPP, or a general dealing account with Hargreaves Lansdown, AJ Bell or Freetrade, this is the tax that quietly adds 0.5% to the price of nearly every UK share you buy, and it is now being rebuilt from the ground up.
The Securities Transfer Tax is not a rate change. HMRC has been careful to frame this as modernisation rather than a tax cut, and the widely quoted 0.5% figure is expected to carry across largely unchanged into the new system. What actually shifts is how the tax is collected. Stamp Duty Reserve Tax currently runs through the CREST electronic settlement system, charged automatically the moment a trade clears; paper Stamp Duty, a near-Victorian relic requiring physical stock transfer forms, still technically applies to the small number of transactions that fall outside CREST. The new tax folds both routes into one self-assessed, fully digital charge, removing the paper-based reporting pathway entirely. HMRC's stated target is to have the legislative framework in place by 2027, with a four-year transitional period covering transactions entered into before the new rules take effect.
What Actually Changes Under the New System
Strip away the policy language and three concrete things are happening at once. They matter to different people for different reasons, and lumping them together under one "tax reform" headline is exactly how the important distinction below gets lost.
- A single Securities Transfer Tax replaces both Stamp Duty and Stamp Duty Reserve Tax
- Filing and payment move fully online, closing the paper stock-transfer-form route that a residual number of off-market transactions still use
- The government wants the legislative framework in place by 2027, and has floated a four-year transition so trades made under today's rules aren't unwound retroactively — a detail brokers had specifically asked HM Treasury to confirm during consultation
None of the three items on that list touches the rate you actually pay. That distinction gets lost in most coverage of the announcement, and it is the single most important thing to understand about this reform before you read anything else written about it.
The Stamp Duty Holiday Already Running — and Where It Stops
This July announcement builds on a change that has already been in force since late 2025. Chancellor Rachel Reeves used the November 2025 Budget to confirm a stamp duty holiday for newly listed London shares: buy stock in a company within three years of its IPO on the London Stock Exchange, and you pay no Stamp Duty Reserve Tax on that purchase at all, against the standard 0.5% that applies everywhere else. The holiday was designed to make new London listings more attractive to buy relative to established blue-chips, and to claw back at least some of the flotation activity that has been drifting toward New York. It sits alongside a package of related measures from the same Budget, including ISA reforms aimed at UK equities and a push to steer more institutional money — pension funds in particular — toward domestic listings rather than overseas index trackers. None of those measures touch the mechanics of how Stamp Duty Reserve Tax is charged; they work on the demand side, trying to make buying UK shares more attractive, while the July 2026 paper works on the collection side, trying to make paying the tax simpler. Treasury officials have been explicit that the two workstreams are separate, even though they land in the same 12-month window and get reported together. A trader deciding whether to hold a newly listed stock past its three-year holiday window needs to track both, because the holiday's expiry date and the STT's 2027 rollout date won't necessarily line up for any given position.
It has not obviously worked yet, or at least not enough. Analysis from broker Peel Hunt earlier this month found that the value of UK-listed companies subject to takeover approaches in the first half of 2026 was 27 times greater than the value of new flotations over the same period. Companies are still leaving the London market through acquisition far faster than new ones are arriving through IPO, stamp duty holiday or no stamp duty holiday, and a purely fiscal incentive on the buying side has done little to change the calculus on the listing side.
Why This Is Happening Now
The backdrop explains the urgency behind HMRC's timetable. Last month's $1.3 trillion flotation of SpaceX on a US exchange has UK market-watchers braced for Anthropic and OpenAI to follow with similarly outsized listings, tilting global index funds further toward American mega-caps and away from London-listed alternatives with each one. At the same time, the Association of Investment Companies has been lobbying government to go further than modernisation and abolish Stamp Duty on shares outright, alongside reversing last year's cut to tax relief on venture capital trusts. AIC chief executive Richard Stone put the case bluntly: in his view, abolishing stamp duty altogether would deliver the single biggest available boost to UK equity markets by cutting the cost of buying in for both retail and institutional money.
The case for going further than the July proposal is genuinely strong, and HMRC's own paper is more cautious than the industry lobby wants — modernisation without a rate cut satisfies almost nobody who is actually trading on cost today. Digitising a tax and lowering a tax are two entirely different projects, and press coverage that treats the STT announcement as a straightforward win for investors does readers no favours when they are trying to work out how much this reform will actually save them. On the current draft, the honest answer is: nothing, yet.
What the Tax Actually Costs You Today
None of this changes what you pay right now. Buy £5,000 of shares in an established FTSE 100 company today — Vodafone, HSBC, Tesco — and £25 of that is Stamp Duty Reserve Tax, deducted automatically by your platform before the trade even settles. Buy £5,000 of a company that listed on the London Stock Exchange within the last three years, and under the November 2025 holiday, that £25 charge does not apply at all, provided the company still meets the qualifying criteria. Exchange-traded funds sit outside this entirely: most ETFs domiciled outside the UK, including the iShares and Vanguard funds that dominate the typical ISA portfolio, are not liable for the 0.5% charge in the first place, because SDRT is scoped to UK-incorporated company shares rather than to fund units regardless of where they're held.
Your ISA Doesn't Shield You From This
Wrapping a trade inside an ISA does nothing to change the stamp duty bill.
The tax attaches to the transaction itself, the transfer of legal title in a UK share, rather than to the account structure holding it afterwards. Whether you buy through a Stocks and Shares ISA with its £20,000 annual allowance, a SIPP, or an unwrapped general investment account, the 0.5% charge — or its Securities Transfer Tax successor from 2027 — applies identically. What the ISA wrapper actually protects is the tax on your gains and dividends afterwards, the Capital Gains Tax and dividend tax you would otherwise owe on returns, not the transaction cost of getting into the position in the first place. Investors sometimes conflate the two, assuming ISA status somehow makes trading itself free; platforms don't help matters by burying the SDRT line item several clicks deep in a contract note most people never open.
What to Watch Before 2027
For most ISA investors buying and holding a handful of index funds, this reform will barely register — you were never liable for SDRT on fund units in the first place, and a switch from stamp duty to Securities Transfer Tax doesn't touch what you already pay. It matters far more if you trade individual UK shares frequently, where the 0.5% compounds fast: someone rebalancing a £50,000 portfolio of individual FTSE stocks twice a year is paying roughly £500 in stamp duty annually before any dealing charges, platform fees or bid-offer spread costs are added on top. That's the segment of investor the AIC is lobbying hardest for, and it's also the segment the government's July paper does the least for, because digitising collection doesn't reduce the bill by a single penny.
If cost genuinely drives your decisions as an active trader, non-UK-domiciled ETFs and US-listed shares remain the more stamp-duty-efficient route today, and that won't change once the Securities Transfer Tax arrives, because the new tax stays scoped to UK securities specifically. Watch the draft finance bill due later this year rather than the July policy paper itself — policy papers set direction, but the legislation that eventually implements the STT is where the real detail, thresholds, exemptions, and whether the three-year listing holiday survives the transition intact, will actually land.
HMRC has said it wants the new framework legislated by 2027, with existing trades protected under a four-year transitional window, which means anyone trading UK shares between now and then is, in practice, still working under rules that have applied in substance since Stamp Duty Reserve Tax was introduced in 1986. The paperwork is changing. The 0.5% mostly isn't, not yet.