Choosing a UK Investment Platform: The Complete Comparison Guide for 2026

The UK retail investment platform market is mature, competitive, and in some respects confusing. Platforms compete on price, fund range, research tools, service quality, and mobile experience. For investors with meaningful portfolios, the difference in annual charges between platforms can run to several thousand pounds per year. The right choice depends on portfolio size, trading frequency, whether you hold funds or ETFs, and whether you want UK or global market access.

This guide covers the major platforms available to UK-based investors in 2026, explains the fee structures honestly, and sets out a framework for choosing.

The Two Fee Models: Percentage vs Flat Fee

Before comparing providers, understanding the structural difference between fee models matters:

Percentage fee: the platform charges a percentage of the value of assets held. Example: 0.45% per year on a £100,000 portfolio = £450/year. If the portfolio grows to £500,000, the same percentage = £2,250/year.

Flat fee: the platform charges a fixed amount per month or year, regardless of portfolio size. Example: £9.99/month = £119.88/year regardless of whether you hold £50,000 or £2,000,000.

The crossover point — where a flat fee becomes cheaper than a percentage fee — depends on the specific rates. For most percentage-fee platforms, the flat-fee alternative becomes cheaper somewhere between £150,000 and £400,000 of assets. Very large portfolios are almost always better served by flat-fee platforms.

Hargreaves Lansdown: Best Service, Higher Cost

Hargreaves Lansdown (HL) is the largest retail investment platform in the UK by assets and customer numbers. It is consistently ranked highest for customer service, research quality, and platform stability.

Fee structure:

• Shares, ETFs, and investment trusts: 0.45% per year, capped at £45/year per account type (ISA, SIPP, dealing account)
• Funds: 0.45% per year (uncapped on ISA, capped at £250/year on SIPP — important for large pension portfolios)
• Trading fees: £11.95 per trade (falls to £5.95 with 20+ trades/month)

Key points:

• The £45/year cap on shares means HL becomes very cheap for equity/ETF portfolios over ~£10,000 (0.45% × £10,000 = £45).
• Funds (unit trusts and OEICs) have no per-account cap — a £500,000 fund portfolio costs £2,250/year in platform fees alone.
• The SIPP fund fee cap of £250/year makes HL more competitive for large SIPP fund portfolios than the basic percentage suggests.
• No additional charge for holding US stocks or most international shares.
• HL provides excellent research, a wide fund range, and strong client money protection procedures.

Best for: investors who value service and simplicity; those primarily holding shares and ETFs (where the cap applies); HL's own Junior ISA and LISA products.

Not ideal for: large fund portfolios (where the uncapped fee is expensive); frequent traders (£11.95 per trade adds up).

Interactive Investor: The Flat-Fee Champion

Interactive Investor (II) charges a flat monthly fee for its main accounts. It is typically the most cost-effective platform for portfolios above approximately £50,000-£100,000.

Fee structure (2026):

• Investor plan: £9.99/month = ~£120/year; includes one free trade per month
• Super Investor plan: £19.99/month = ~£240/year; includes two free trades per month; lower trading fees
• Trades: £3.99 per trade (Investor plan after free trade), £3.99 (Super Investor)
• Shares, funds, and ETFs all charged the same flat fee (no percentage escalation)

Key points:

• The flat fee model means a £500,000 portfolio costs the same as a £50,000 portfolio.
• Additional accounts (SIPP, ISA, trading account) are available under the same plan fee, not separately priced.
• Strong fund supermarket — access to thousands of funds and ETFs.
• Research and tools are good but do not match HL's level of polish.
• II is owned by Abrdn (Standard Life Aberdeen) — a regulated, institutional-grade custodian.

Best for: investors with portfolios above £100,000; those wanting to hold SIPP, ISA, and trading account without incremental fees; cost-conscious investors.

Not ideal for: investors with small portfolios (flat fee is proportionally expensive for a £10,000 ISA).

AJ Bell: Mid-Range Quality

AJ Bell (including its Dodl app for simplified investing) occupies the middle ground — generally cheaper than HL for similar products, not as cheap as II for large portfolios.

Fee structure:

• Shares/ETFs: 0.25% per year, capped at £3.50/month (£42/year) per account
• Funds: 0.25% per year
• Trades: £9.95 (shares/ETFs), £1.50 (funds)

Key points:

• The 0.25% shares/ETF rate with £42/year cap is competitive — roughly half the cost of HL for equity portfolios above £17,000.
• Fund costs (0.25%) are lower than HL (0.45%) without the per-fund cap structure.
• AJ Bell has strong pension (SIPP) functionality and an excellent awards track record.
• SIPP tools include flexible drawdown and annuity comparison services.

Best for: medium portfolios (£50,000-£500,000); investors wanting a balance of cost and service quality; SIPP holders at or near retirement.

Vanguard UK: Cheapest for Vanguard-Only Portfolios

Vanguard's UK platform offers access exclusively to Vanguard funds and ETFs. For investors who want a simple, passive, low-cost portfolio using Vanguard products only, it is the cheapest option.

Fee structure:

• Account fee: 0.15% per year, capped at £375/year across all accounts
• No trading fees on Vanguard funds
• ETF trades: £7.50 per trade

Key points:

• For portfolios up to £250,000 (where 0.15% = £375 = the cap), this is the lowest-cost percentage-fee option among major platforms.
• Above £250,000, the cost is flat at £375/year — making it extremely competitive for large portfolios, provided you want only Vanguard products.
• The product restriction (Vanguard funds only) means no access to iShares ETFs, Fundsmith, Baillie Gifford funds, or any non-Vanguard product.
• Suitable as a satellite platform for the portion of a portfolio held in Vanguard index funds, while using another platform for broader holdings.

Best for: passive index investors who want only Vanguard funds; large portfolios above £250,000 invested entirely in Vanguard products.

Not ideal for: investors wanting active funds, bonds funds from other providers, or thematic ETFs.

Fidelity UK: Strong Fund Range

Fidelity offers a broad platform with particular strength in actively managed funds.

Fee structure:

• Shares/ETFs: 0.35% per year, capped at £7.50/month (£90/year)
• Funds: 0.35% per year (no cap)
• Trades: £7.50 per trade (regular investing from £25/month: no dealing charge)

Key points:

• Broad access to third-party funds — one of the widest fund supermarkets available.
• Fidelity's own proprietary research and fund range is strong; Fidelity Select 50 provides a curated list.
• Regular investment service at no dealing charge is excellent for monthly investors.
• Fund fees are not capped — expensive for large fund portfolios.
• ISA, SIPP, and Junior ISA all available.

Best for: active fund investors; regular investors taking advantage of the no-charge monthly investment service; investors wanting research alongside trading.

Interactive Brokers: Cheapest for US Stocks and Frequent Traders

Interactive Brokers (IBKR) is an institutional-grade brokerage platform originally designed for professional traders. It is now widely accessible to retail investors and is the most cost-effective option for holding US and non-UK equities, frequent trading, and currency conversion.

Fee structure:

• Monthly minimum inactivity fee: $0 for IBKR Lite; variable for IBKR Pro
• UK shares: 0.05% of trade value (min £3)
• US shares: $0.005 per share (min $1)
• Currency conversion: 0.002% of converted amount (far cheaper than HL or II's typical FX conversion charges)
• No custody fee for holding assets

Key points:

• No platform annual fee on IBKR Lite — pure transaction costs.
• Lowest FX conversion costs in the market — significant for investors trading US or international equities.
• Access to US options, futures, commodities, and CFDs — not available on HL or II.
• Interface is professional-grade and less friendly for beginners.
• IBKR is US-regulated and UK FCA-regulated; FSCS cover applies to UK clients for the first £85,000 of investments.
• Not a fund supermarket — limited access to UK unit trusts; best for shares and ETFs.

Best for: frequent traders; investors with significant US or international equity holdings; those sensitive to FX conversion costs.

Not ideal for: fund investors; those who prioritise a simple, consumer-friendly interface.

FSCS Protection and Platform Safety

All major UK platforms are FCA-regulated and covered by the Financial Services Compensation Scheme (FSCS) for investments up to £85,000 per eligible claimant per firm. Above this threshold, protection depends on the platform's client money segregation arrangements — specifically, whether client assets are held separately from the platform's own assets in nominee accounts.

For portfolios significantly above £85,000 on a single platform:

• Client assets are legally segregated from platform assets at all major platforms — if the platform fails, assets should be returned even above £85,000.
• FSCS covers only instances where assets are lost due to fraud or negligence, not market losses.
• Spreading assets across two or three platforms is a practical approach for portfolios above £500,000.

Investments carry market risk and can fall as well as rise in value. Platform fees are subject to change; always verify current fee schedules directly with the provider before making decisions. This article reflects platform fee structures as at June 2026.

How Global Investments Can Help

Global Investments manages discretionary investment portfolios for HNW clients, using custodian platforms and arrangements appropriate to each client's portfolio size, tax position, and access needs. We can advise on the most efficient custodial structure for your assets, including multi-platform arrangements for large portfolios. Contact us to discuss your investment platform needs.