Buy £2,000 of a FTSE 100 company through an online broker and the contract note will show a line you never asked for: stamp duty reserve tax, £10. It is not a misprint and not a broker fee. It is a tax on buying shares in UK companies, charged at 0.5% of what you pay, and it lands on almost every purchase a private investor makes.
It also goes unnoticed by most people, because it never appears in the quoted share price. The cost only becomes visible when you look at what you actually own afterwards. Over a long holding period, that is fine. Over a year of active dealing, it is one of the largest predictable costs you face.
Two charges, one rate
Stamp duty and stamp duty reserve tax are two versions of the same 0.5% charge.
Stamp duty is the older tax, paid when shares change hands using a paper stock transfer form. Stamp duty reserve tax, usually shortened to SDRT, is its electronic twin, collected automatically through CREST when shares move between accounts without any paper involved.
If you deal online, you pay SDRT. The rate is 0.5% of the consideration — the amount you pay for the shares. It is charged on the price you agreed, not the market value, and not on your broker's commission. Rounded to the nearest penny, it is collected around settlement and passed to HMRC.
When the charge is triggered
The test is where the company is incorporated, not where its shares are listed or where you place the trade. Buy a UK-incorporated company through a US broker and the tax still applies. Buy a US-incorporated company through a UK broker and it does not.
Three practical points are worth holding on to:
- It applies to purchases, not sales. The buyer pays. Selling shares in a UK company does not generate SDRT, so a buy-and-sell round trip costs you 0.5% once, on the way in.
- New shares are different. Subscribing for shares in a placing, a rights issue or an IPO is not a transfer of existing shares, so the 0.5% charge generally does not arise. You are buying from the company, not from another investor.
- Paper has its own rules. Transfers using a stock transfer form attract stamp duty at the same 0.5%, and the form must be stamped before the registrar will register you as the owner. Transfers where the consideration is £1,000 or less are exempt from stamp duty.
What escapes stamp duty and SDRT
Given the charge is 0.5%, exemptions matter more than they first appear. The main ones:
- Shares in companies incorporated outside the UK. A US-listed company, or an Irish-domiciled exchange-traded fund, sits outside the charge. This is a large part of why so many ETFs sold across Europe are domiciled in Ireland rather than London.
- Shares on recognised growth markets. Shares admitted to trading on AIM, and on other markets HMRC recognises as growth markets, have been exempt from stamp duty and SDRT since 2014.
- Gilts, corporate bonds and most loan capital. Fixed-income securities are outside the charge, which is one reason bond funds look cheaper to trade than equity funds.
- UK unit trusts and open-ended investment companies. Buying units in an authorised unit trust or shares in an OEIC does not trigger the 0.5% charge, though the fund may apply its own dealing costs.
- Certain institutional transactions. Market makers, charities and stock-lending arrangements operate under their own reliefs. Useful to know they exist; not much help to a private investor.
One warning. An exemption is a tax point, not an investment case. AIM shares are exempt, and they are also smaller, less liquid and more volatile than the main market. Let the tax follow the decision, never lead it.
An ISA or SIPP will not shelter you
This is the most common misunderstanding about the tax. Tax wrappers protect your dividends and capital gains from further tax. They do not remove transaction taxes.
Buy a UK company inside an ISA or a SIPP and you still pay 0.5%. The wrapper changes nothing about the charge itself. What it does mean is that if your tax-sheltered space is limited, the assets you hold there should be the ones generating the most taxable income and gains — not necessarily the ones that dodge stamp duty.
What it does to your returns
On a single purchase, the figures are small. £5,000 of shares costs £25. £10,000 costs £50. If you buy and hold for a decade, you pay it once and it fades into the background.
Frequency is what turns it into a real number. Suppose you invest £5,000 a month into UK shares. That is £60,000 of purchases a year and £300 in stamp duty — before commission, before the spread, before any platform fee. If your portfolio is worth £60,000, you have handed over half a percent of it in a single year purely to move money into the market.
It also shifts your break-even point. Buy £10,000 of shares and pay £50 in tax, and the position has to gain roughly 0.5% before you are level. Add a £10 commission and a 0.2% spread and the real hurdle is closer to 0.8%. That is the number to hold in your head when a short-term trade looks appealing.
The other lines on the contract note
Stamp duty is rarely the only charge. Look at the full breakdown:
- Commission or dealing charge — often a flat fee, which hurts small trades disproportionately.
- The spread — the gap between the buying and selling price, invisible but real.
- The PTM levy — a £1 charge on transactions of £10,000 or more in relevant UK securities. Trivial, but it explains the odd pound on your statement.
- FX conversion — if you buy overseas shares, the currency charge can easily exceed 0.5%.
Keeping the cost in proportion
A few habits keep this tax where it belongs — an annoyance rather than a drag.
- Trade less, and in larger amounts. Two £5,000 purchases cost the same in stamp duty as one £10,000 purchase, but only half the commission.
- Use the exemptions deliberately. If a UK and an overseas fund give you the same exposure at similar cost, the one outside the charge leaves more in your account.
- Keep a simple record of dealing costs. Once a year, add up stamp duty, commission and FX. The total is usually larger than people expect, and it is the clearest argument for a longer holding period.
- Do not let a 0.5% charge decide your portfolio. Avoiding a company you want to own for a decade to save a one-off £50 is usually a poor trade.
Tax rules change, and the treatment of a particular security can be more nuanced than a general rule suggests — especially with depositary receipts, funds with unusual structures, and anything held through an overseas broker. For large or complicated transactions, check with a qualified tax adviser before you deal.
Photo: stevepb / Pixabay
