Guides

The Cheapest Stocks & Shares ISA by Portfolio Size (2026)

Which UK investment platform costs the least for your portfolio? A quick-reference guide from £5,000 to £500,000.

Updated 15 April 2026 · 5 min read

Platform fees have a surprisingly large impact on long-term returns. At 0.45% on a £100,000 portfolio, you’re paying £450/year — money that could be compounding for you instead.

Here’s a quick-reference guide to the cheapest platforms at different portfolio sizes, assuming you invest in funds and trade monthly.

Under £10,000

Winner: InvestEngine or Trading 212 (£0/year)

Both charge nothing for their platform fee. InvestEngine focuses on ETFs; Trading 212 covers ETFs and shares. If you’re starting out, these are hard to beat.

Freetrade’s GIA (general investment account) is also free. Their ISA costs £5.99/month — hard to justify on a small portfolio.

£10,000–£30,000

Winner: Vanguard (approx. £15–£45/year)

Vanguard charges 0.15% capped at £375/year. On a £20,000 portfolio that’s £30/year — cheaper than any flat-fee platform.

HL and Fidelity charge more (0.45% and 0.35% respectively) but are still relatively affordable at this size.

£30,000–£80,000

Winner: varies — use the calculator

This is the transition zone. Flat-fee platforms start to become competitive. At around £50,000, Interactive Investor’s £143.88/year ISA fee begins to undercut HL’s percentage-based charge.

Use our calculator with your specific portfolio size.

£80,000–£250,000

Winner: Interactive Investor or Freetrade

At this range, percentage-based fees are painful. HL charges £360–£1,125/year on a £80k–£250k portfolio.

ii at £143.88/year is dramatically cheaper. Freetrade’s ISA at £71.88/year is cheaper still — though its investment range is more limited.

Over £250,000

Winner: Interactive Investor (£143.88/year)

Above £250,000, HL’s fee steps down to 0.25% — still thousands of pounds annually. ii remains flat at £143.88/year regardless of portfolio size.

AJ Bell’s £42/year cap applies to ETFs and shares only (not funds), so check which asset type applies to you.

The quick reference table

Portfolio HL AJ Bell ii Vanguard InvestEngine
£10,000 £45 £25 £144 £15 £0
£25,000 £113 £63 £144 £38 £0
£50,000 £225 £125 £144 £75 £0
£100,000 £450 £250 £144 £150 £0
£250,000 £1,125 £625 £144 £375 £0
£500,000 £1,500 £625 £144 £375 £0

Assumes funds, ISA, monthly trading. Figures are approximate — verify at source.


Fee estimates based on published rates as of April 2026. Always verify current fees directly with your provider.