What Is a Platform Fee? UK Investment Charges in 2026

Two investors hold the exact same global index fund. One pays £42 a year to hold it; the other pays £700. Same fund, same market, same returns before costs — the entire gap is the platform fee. Get this one number wrong and you can hand your broker more than your fund manager over a decade.

This is platform fee explained for UK investors in plain numbers: what the charge is, how it differs from the fund fee buried inside your ETF, and — the part most comparison tables skip — the exact pot size where a flat fee beats a percentage fee. If you want to put the theory to work on real funds, our structured ETF investing course walks through cost-aware fund selection end to end.

What is a platform fee?

A platform fee is the annual charge an investment platform — your ISA, SIPP or general account provider — takes for holding and administering your investments. It pays for custody, the website and app, tax reporting and client money protection. It is charged whether your investments rise or fall, and it sits entirely separate from what the funds themselves cost.

Think of it as rent on the shelf, not the price of the product on it. You can own a fund costing 0.07% a year and still pay a platform 0.35% a year to keep that fund in your account. Both come out of your money; only one appears as an obvious line.

How it is collected varies. Most platforms take the fee monthly or quarterly, either from cash in your account or by selling a sliver of your holdings if there is no cash. That matters: a percentage fee skimmed by selling units quietly shrinks the position you are trying to grow. It also means the headline rate is only ever a starting figure — two platforms quoting "0.25%" can still cost you different amounts once you factor in how and when they take it, and whether they cap it.

Platform fee vs fund fee: what's the difference?

The platform fee is what the platform charges you. The fund fee — the Ongoing Charges Figure (OCF), sometimes shown as the TER — is what the fund charges, and it is deducted daily inside the fund before the price you see. It never shows up as a line on your statement; you have to read the fund's factsheet or KIID to find it. If you want the full breakdown of that second number, see our guide to how a fund's expense ratio eats your returns.

Your real cost is both stacked together. A fund with a 0.45% OCF held on a platform charging 0.25% gives a combined drag of 0.70% a year. On a £50,000 pot that is £350 every year — £125 to the platform, £225 to the fund. Comparing platforms on their headline fee alone, while ignoring the OCF of the funds you actually buy, is how people pick the "cheap" option and still overpay.

Percentage vs flat fees: which model is cheaper?

Here's the catch: there is no single cheapest model — it depends entirely on how much you hold. A percentage fee is a fixed slice of your pot, so it grows as you do. A flat fee is a fixed pound amount, so its bite shrinks as a share of a bigger pot.

The trade-off in one view

The decisive number is the crossover point — the pot size at which a flat fee becomes cheaper than a percentage fee. Below it, percentage wins; above it, flat wins. The chart shows exactly where those lines cross.

What this means for you: against a £71.88 flat fee, a 0.35% percentage platform becomes the more expensive option once your pot climbs above about £20,500; a 0.25% platform stays cheaper until roughly £28,750. Below those pot sizes the percentage fee wins. Find where your own pot sits on that line before you judge any platform "expensive".

UK investment platform fees compared (2026)

Real UK platforms blend these models, and several cap the percentage so it stops biting past a point. The table below sets out the headline account charge each one applied in 2026. Treat it as a map of the models, not a league table — the right choice depends on your pot size and what you hold.

Source: Vanguard UK, AJ Bell, Hargreaves Lansdown, interactive investor and InvestEngine published charges schedules, 2026. Fund dealing and FX charges are extra and vary by provider.

Read the caps, not just the rates. AJ Bell's 0.25% on shares and ETFs stops rising once it hits £42 a year — around a £16,800 pot — so a "percentage" platform can behave like a flat one above the cap. A provider that looks dear on paper may be the cheapest you can hold once the cap is applied. The headline rate is the start of the comparison, never the end of it.

How to calculate your all-in annual cost

Stop comparing single fees and compare the total. Your real cost of ownership is the platform fee plus the weighted OCF of your funds plus any dealing and FX charges you actually incur. Work it out in four steps:

1. Platform fee. Apply the model to your pot. Percentage: pot × rate (e.g. £50,000 × 0.35% = £175). Flat: the annual subscription (e.g. £71.88). Apply any cap.
2. Fund OCF. Weight each fund's OCF by how much you hold in it. A single global tracker at 0.22% on £50,000 is £110.
3. Dealing and FX. Add per-trade commissions and the FX spread on any overseas holdings — small for a buy-and-hold investor, real for a frequent trader.
4. Total and express it as a percentage. Add the pounds, divide by your pot. £175 + £110 = £285 on £50,000 is 0.57% all-in — the only figure worth comparing across platforms.

Run that same sum for a flat-fee platform at your pot size and you will see the switch instantly. At £50,000 the flat £71.88 plus the same £110 OCF is £181.88, or 0.36% all-in — a fifth cheaper, for an identical portfolio. The bigger your pot, the wider that gap opens.

The 20-year cost of an avoidable fee gap

Here's the part that stings: a small fee difference is not a small amount of money, because fees compound against you. Every pound paid in charges is a pound that stops earning returns for the rest of your investing life.

Take a £100,000 pot growing at 6% a year for 20 years. Pay 0.30% a year more than you needed to — the kind of gap between a capped and an uncapped platform — and you end with about £303,000 instead of £320,700. That 0.30% quietly costs you roughly £17,700. Not the £6,000 a straight-line guess (20 × £300) suggests — nearly three times as much, because each year's fee also forfeits the growth it would have earned.

That is why the platform fee deserves the same scrutiny as the funds you choose. It is a certain, recurring cost you fully control, in a game where almost nothing else is certain. (Illustration only: assumes a constant 6% return and level charges; real returns vary.)

When switching platforms saves you money

The data says otherwise to "set and forget": many investors stay on a percentage platform long after a flat fee would have been cheaper, quietly overpaying every year. If your pot has grown past the crossover for your platform's rate, switching is often the single highest-return decision available to you — a guaranteed saving, not a market bet.

The friction people fear is mostly avoidable. You do not sell up and start again; you transfer the account in specie, keeping your tax wrapper intact. Our guide on how to transfer an ISA without losing its tax-free status covers the mechanics, and because platform charges differ by account type, it helps to know how ISAs, GIAs and SIPPs compare before you move.

Before you switch, check three things: any exit or transfer-out fee the old platform charges, whether your current funds are available on the new one, and how long the market is out of action during an in-specie move. A £25 exit fee is irrelevant if the switch saves you £300 a year — but a fund you cannot re-buy is a genuine reason to stay.

Frequently asked questions

This article is educational content, not investment advice or a recommendation of any platform. Charges are as of 2026 and change often — always confirm current rates on each provider's own charges page before deciding.