Best Stocks and Shares ISA Platforms, Ranked by Cost (2026)

Ask "what are the best stocks and shares ISA platforms?" and the honest answer is: it depends on the size of your pot. The cheapest platform for a £5,000 ISA is rarely the cheapest for a £100,000 one, because providers charge in two very different ways. Get the match wrong and the fee drag quietly eats years of returns.

This ranking lines up six of the main UK stocks and shares ISA platforms by the one number most comparison pages bury: the annual platform fee you actually pay. The deciding criterion here is cost, not brand. Once you can see how a flat fee and a percentage fee behave as your money grows, choosing becomes a 10-minute decision rather than a leap of faith. If you want the structured version of this skill, our structured UK and US stock market training covers how costs compound against a portfolio over time.

Which stocks and shares ISA platform is cheapest?

On headline platform fees, the cheapest UK stocks and shares ISA platforms are the free, ETF-only providers such as InvestEngine, which charges £0 to hold a do-it-yourself ETF portfolio. For investors who want funds and individual shares too, a low flat-fee or capped-percentage platform usually costs least once the pot passes roughly £30,000; below that, a low percentage fee like Vanguard's is typically cheaper. In short, the "cheapest ISA platform" is a moving target that depends on how much you hold and what you hold.

*Headline platform/custody fee only, on funds unless stated; fund charges (OCF), dealing and FX fees are extra. Figures are 2026 headline rates as reported by UK investment-platform fee analysis - providers change pricing, so confirm current rates before you open an account. Source: AJ Bell, Fidelity, Vanguard, Hargreaves Lansdown, interactive investor and InvestEngine published fee schedules, as reported 2026.

Read the table top to bottom and one thing stands out: the gap from first to last on a £20,000 pot is only about £90 a year. That sounds trivial. It is not - because on a larger pot the percentage-fee platforms keep climbing while the flat and capped ones stand still. The ranking you see above is for a mid-sized ISA; it reshuffles sharply at the extremes, as the next sections show.

The platforms ranked by cost, from cheapest to priciest

Here is what each platform charges and, more usefully, the one situation where it is the right call. The order below follows the £20,000 scorecard above.

1. InvestEngine - free, if you only want ETFs

InvestEngine charges no platform fee at all for a self-directed ETF ISA. That is as cheap as the headline number gets. The trade-off is range: you can hold exchange-traded funds, but not actively managed funds or individual company shares. For a beginner building a simple, diversified index portfolio, that limitation may not matter at all. It is worth checking whether the platform charges a dealing fee or an FX fee on US-listed ETFs, because those small percentages are where a free platform quietly earns its keep.

2. Vanguard - cheapest percentage, inside its own walls

Vanguard's UK platform charges 0.15% a year, capped at £375, and now offers a £4-a-month flat option that works out at £48 a year for pots under about £32,000. Either way it is very cheap. The catch is that you can only buy Vanguard's own funds and ETFs - no shares, no rival fund houses. If you are happy owning a Vanguard index fund and nothing else, it is hard to beat.

3. AJ Bell - the cap that protects big pots

AJ Bell charges 0.25% a year on funds, but its custody fee on shares and ETFs inside an ISA is capped at £3.50 a month, or £42 a year. That cap is the headline feature: a £200,000 share portfolio pays the same £42 as a £20,000 one. For investors mixing funds with a decent slug of shares or ETFs, it is one of the most balanced options on cost.

4. interactive investor - the flat fee that ages well

interactive investor breaks from the percentage model entirely, charging a flat monthly subscription - roughly £60 to £72 a year depending on the plan. On a £10,000 ISA that looks expensive next to a 0.15% rival. On a £150,000 ISA it looks like a bargain, because the fee never moves. Flat pricing is a bet on your pot growing, and most long-term investors win that bet. One quick test: divide the annual flat fee by your current balance. If the result is already below about 0.2%, the flat plan is working in your favour today, not just in some future year.

5. Fidelity - mid-table, with a small-pot wrinkle

Fidelity charges 0.35% a year on investments, with the custody fee on shares and investment trusts capped at around £90. There is a wrinkle for small balances: without a regular savings plan, a flat £90 fee can apply below £25,000, which makes it pricey for a brand-new ISA. Once your pot is larger and fund-based, the 0.35% rate puts it squarely in the middle of the field.

6. Hargreaves Lansdown - you pay for the full-service breadth

Hargreaves Lansdown is the UK's largest platform and historically the priciest on headline funds fees, at 0.45% a year - which is £90 on £20,000 and £450 on £100,000 of funds. You get the widest choice, strong research and service in return. Note that HL announced reductions to its charges during 2026, so the exact rate is worth checking directly before you judge it on the old number.

Flat fee vs percentage: which wins for your portfolio?

This is the decision that actually sets your cost. A percentage fee takes a slice of everything you hold, so it rises every time your pot grows. A flat fee is a fixed amount that does not care whether you hold £10,000 or £1,000,000. Somewhere between those two lines is a crossover - the portfolio size where the flat fee becomes the cheaper deal.

Using a typical flat plan of about £72 a year, the crossover against each percentage rate falls roughly where you would expect: around £16,000 against a 0.45% platform, about £20,500 against 0.35%, near £28,750 against 0.25%, and only at about £47,900 against a very low 0.15% rate. Below your crossover, percentage wins; above it, flat wins. The chart below shows why the gap gets so wide at scale.

What to do with this: if you are investing for decades, assume your pot will grow into the right-hand end of that chart. A fee that is painless at £20,000 can cost you hundreds a year at £100,000, and that money is gone whether markets rise or fall. Picking a structure that stays cheap as you grow is one of the few guaranteed edges in investing.

One more layer decides your real bill: the costs the platform fee hides. Every fund carries its own ongoing charge, typically 0.1% to 0.9% a year, paid to the fund manager rather than the platform. Buying and selling can trigger dealing fees, and holding US shares usually adds a foreign-exchange fee of roughly 0.15% to 1.5% each time you convert currency. A platform with the lowest headline fee can still be the dearest for how you actually invest, so total the whole stack - platform, fund charges, dealing and FX - on your own holdings before you decide.

How do you choose the right ISA platform for you?

Forget "best overall" and match the platform to your situation. Four honest routes:

You are starting small and simple. A free ETF platform or a very low percentage fee keeps costs near zero while your pot is modest. This is also the stage to learn the difference between account types - our guide to how a cash ISA compares with a stocks and shares ISA is the right starting point before you pick a provider.

You hold mostly funds and the pot is growing. Watch the crossover. Once you are past roughly £30,000 in funds, a capped or flat-fee platform usually beats an uncapped percentage one. If the idea of a "platform fee" is still fuzzy, our explainer on what a platform fee is and how UK charges stack up breaks down every layer.

You hold mainly shares or ETFs. A custody cap is your friend - it freezes the fee no matter how large the holding grows. You want one account for everything. A full-service platform costs more but spares you juggling providers; decide whether that convenience is worth the drag. It also helps to know where the ISA sits among the other wrappers, which our ranking of ISA, GIA and SIPP accounts lays out.

Frequently asked questions

Investing involves risk, including possible loss of capital. This article is educational content, not investment advice.

This ranking is an educational comparison only - not a recommendation or endorsement of any provider, and not investment advice. Platform pricing changes; assess any platform against your own circumstances and current published fees before using it.