The £25,000 Test: What Platform Fees Really Cost You
A £25,000 ISA portfolio spread across basic index funds will cost you anywhere from £0 to £112.50 per year in platform fees alone, depending on where you invest. Over 10 years, assuming 7% annual growth, this seemingly small difference compounds into a staggering £3,847 gap between the cheapest and most expensive platforms.
We've analysed the total cost of ownership across the UK's five largest ISA platforms using a standardised portfolio of low-cost index funds. The results reveal how percentage-based fees become wealth destroyers as your pot grows, while fixed-fee models reward larger investors.
The Real Cost Breakdown: Five Platforms Compared
Trading 212: £0 annual platform fee on ISAs
- Year 1 cost: £0
- Year 5 cost: £0
- Year 10 cost: £0
- Total fees paid over 10 years: £0
Vanguard UK: 0.15% annual platform fee (capped at £375)
- Year 1 cost: £37.50
- Year 5 cost: £52.13
- Year 10 cost: £73.12
- Total fees paid over 10 years: £525
Photo: Vanguard UK, via e7jei3voicd.exactdn.com
AJ Bell Youinvest: 0.25% annual platform fee (first £250,000)
- Year 1 cost: £62.50
- Year 5 cost: £86.89
- Year 10 cost: £121.87
- Total fees paid over 10 years: £875
Interactive Investor: £9.99 monthly fee (£119.88 annually)
- Year 1 cost: £119.88
- Year 5 cost: £119.88
- Year 10 cost: £119.88
- Total fees paid over 10 years: £1,199
Hargreaves Lansdown: 0.45% annual platform fee
- Year 1 cost: £112.50
- Year 5 cost: £156.40
- Year 10 cost: £219.37
- Total fees paid over 10 years: £1,574
The Tipping Point: When Fixed Fees Beat Percentages
The mathematics change dramatically based on your portfolio size. Interactive Investor's £9.99 monthly fee looks expensive for smaller pots but becomes competitive once you hit £26,640. At £50,000, it's cheaper than AJ Bell. At £100,000, it significantly undercuts Hargreaves Lansdown.
For portfolios above £150,000, Interactive Investor's fixed fee model saves thousands compared to percentage-based competitors. A £200,000 ISA would pay £1,750 annually at Hargreaves Lansdown versus £119.88 at Interactive Investor – a difference of £1,630 per year.
The Fund Selection Trap
Platform fees are only half the story. Some platforms push expensive active funds while others offer comprehensive ranges of low-cost index trackers. Hargreaves Lansdown's "Wealth 150" list includes funds with ongoing charges of 1.5% or more, while Vanguard UK focuses exclusively on its own low-cost range.
A typical "balanced" portfolio on Hargreaves Lansdown might carry total annual costs of 1.8% (0.45% platform fee plus 1.35% fund charges). The same allocation using Vanguard funds costs 0.35% total. On a £25,000 portfolio, that's £450 versus £87.50 annually – a five-fold difference.
Trading Frequency Matters
Active traders face additional costs. Hargreaves Lansdown charges £11.95 per trade for shares and ETFs. Interactive Investor includes unlimited trades in its monthly fee. Trading 212 offers commission-free trading but makes money through foreign exchange spreads.
Investors making monthly contributions through regular investing services should check the charges. Some platforms charge £1.50 per monthly investment, adding £18 annually to your costs.
The Switching Decision Framework
Portfolio under £10,000: Trading 212 or Vanguard UK offer the lowest total costs.
Portfolio £10,000-£50,000: Vanguard UK provides the best balance of low fees and fund choice for passive investors.
Portfolio £50,000-£100,000: Interactive Investor becomes competitive, especially for investors wanting access to international markets and investment trusts.
Portfolio above £100,000: Interactive Investor's fixed fee model offers significant savings. Consider splitting across multiple platforms to maximise ISA allowances.
The Transfer Process: What You Need to Know
ISA transfers must be done formally to preserve the tax wrapper. Never withdraw and re-invest, as you'll lose the tax benefits permanently. Most platforms offer free inbound transfers but may charge for outbound moves.
Transfer times vary from two weeks (cash ISAs) to six weeks (stocks and shares ISAs). During this period, you cannot trade, so timing matters if markets are volatile.
What to Watch in 2026
Platform fee wars are intensifying as digital challengers undercut traditional providers. Trading 212's zero-fee model pressures competitors, while regulatory changes may force greater fee transparency.
The FCA's ongoing review of platform charges could introduce caps or standardised disclosure requirements. Brexit has also limited access to some European ETFs, potentially affecting fund choice and costs.
The verdict: For most UK investors, platform fees matter more than marketing suggests – a 0.45% annual charge becomes a £90,000 wealth destroyer over 30 years on a £200,000 portfolio.
This article is for informational purposes only and does not constitute financial advice. Your capital is at risk. Past performance is not a reliable indicator of future results.