ETFs explained: how they work, costs and what to watch
Quick answer: An exchange-traded fund (ETF) is a basket of investments — usually tracking an index — that trades on a stock exchange like a single share.
An exchange-traded fund (ETF) is a basket of investments — usually tracking an index — that trades on a stock exchange like a single share. ETFs combine the diversification of a fund with the price flexibility of a share, and have become the default low-cost investment for many UK investors. This guide explains how they work, what to look for and the UK-specific tax wrinkles.
Last reviewed:
Primary source: https://www.fca.org.uk/investors/exchange-traded-products
How an ETF differs from a unit trust or OEIC
Traditional UK funds (unit trusts and OEICs) are priced once a day at a single 'NAV'. An ETF trades all day on an exchange at a price set by buyers and sellers, very close to the value of its underlying holdings.
ETFs let you place limit orders, see live prices and trade in seconds. They are also usually cheaper than equivalent active funds — and often slightly cheaper than equivalent passive OEICs.
The trade-off is a dealing cost on every trade and the bid-offer spread (the gap between buy and sell prices). For long-term buy-and-hold investors these are minor; for frequent trading they add up.
Physical vs synthetic — what's inside the ETF
Physical ETFs actually hold the underlying assets — for example, a FTSE 100 ETF owns the actual 100 companies in roughly index proportions.
Synthetic ETFs use a swap with an investment bank to deliver the index return rather than owning the underlying assets. They are common for hard-to-access markets and commodities. Counterparty risk is mitigated by collateral, but it is an additional layer of complexity worth understanding.
For most UK investors building a long-term core portfolio, physical UCITS ETFs from major issuers are the simpler default.
The UK 'reporting status' rule
Outside an ISA or SIPP, gains on overseas funds that do NOT have UK 'reporting fund status' are taxed as income at up to 45%, not at the (lower) Capital Gains Tax rates. This rule mainly catches US-domiciled ETFs that UK investors sometimes buy directly.
Reporting status is granted by HMRC and almost all UCITS ETFs from major issuers (iShares, Vanguard, Invesco, Amundi, HSBC) have it. Check the factsheet or KIID — it will say 'UK Reporting Fund Status: Yes'.
Inside a Stocks & Shares ISA or SIPP the rule doesn't matter — all gains and income are tax-free in the wrapper. The reporting-status trap only affects taxable general investment accounts.
Costs to count
Ongoing Charges Figure (OCF): the annual fund cost, deducted continuously from NAV. Mainstream index ETFs are typically 0.03–0.30% a year.
Spread: the gap between buy and sell prices. Tight spreads (0.05–0.10%) are normal for large, liquid ETFs; wider for niche or thinly traded ones. The mid-price is roughly the NAV.
Platform fees: percentage or flat. ETF dealing usually carries a small per-trade fee (£0–£9.95) on percentage platforms; flat-fee platforms often include unlimited dealing in their monthly fee.
Stamp Duty Reserve Tax: not charged on ETFs (an explicit exemption). UK-listed individual shares attract 0.5% SDRT on purchase.
Common questions
- What's the difference between an ETF and a tracker fund?
- Both passively track an index. A tracker fund (OEIC/unit trust) is priced once daily; an ETF trades live on the exchange. For long-term ISA investors the practical difference is small — both work. ETFs typically have lower headline OCFs; OEICs sometimes have no dealing charges on percentage platforms.
- Can I buy US-listed ETFs like VOO or QQQ?
- Most UK retail platforms don't allow direct purchase of US-listed ETFs by retail investors because they don't comply with UK PRIIPs disclosure rules. Use the UCITS UK/EU equivalent (e.g. VUAG for an S&P 500 tracker). UCITS versions also avoid the 'non-reporting fund' tax trap.
- Are ETFs covered by the FSCS?
- The ETF's underlying assets are held in trust separately from the issuer, so even if the issuer fails, the assets are protected. The FSCS protects against the failure of an authorised platform or stockbroker — usually up to £85,000 of cash and investments per person.
- How are ETF dividends taxed?
- Inside an ISA or SIPP: no tax on dividends. Outside a wrapper: dividends from distributing ETFs use your £500 Dividend Allowance (2026/27) then are taxed at 8.75% (basic), 33.75% (higher) or 39.35% (additional). Accumulating ETFs reinvest dividends inside the fund, but the income is still taxable each year — and you also need to track 'equalisation' adjustments to avoid double counting on sale.