The Wealth Wingwoman Audit
Audited by Valerie Vance"The clash between Interactive Investor (ii) and AJ Bell is the defining heavyweight title fight of the UK retail investment landscape: Manchester-based FTSE 250 stalwart AJ Bell versus Edinburgh-backed flat-fee titan Interactive Investor (owned by global asset manager abrdn). Both desks operate under top-tier Financial Conduct Authority (FCA) supervision. Both provide statutory protection up to £85,000 under the Financial Services Compensation Scheme (FSCS). Both offer comprehensive wrappers across Stocks & Shares ISAs, Self-Invested Personal Pensions (SIPPs), Junior ISAs (JISAs), and General Investment Accounts (GIAs). Both provide whole-of-market access spanning thousands of UK and international equities, investment trusts, exchange-traded funds (ETFs), open-ended investment companies (OEICs), and UK Gilts. Assuming they cost roughly the same because both are established, low-cost British platforms is an expensive mistake. One desk is a percentage-based platform that charges 0.25% on mutual funds but introduces an aggressive, investor-friendly cap on shares and ETFs (£42/year in an ISA, £120/year in a SIPP, and £0 in a Dealing Account) alongside access to a government-subsidized Lifetime ISA (LISA). The other is a flat-fee subscription engine: charging a flat monthly fee (£5.99 on Core, £14.99 on Plus) that includes your SIPP, ISA, and GIA under a single price point—rendering platform percentage drag obsolete as your wealth compounds into the six figures, but charging an ongoing subscription even if your portfolio is small. Let’s look at the engine block to see where your capital actually compounds with the highest operational efficiency."
The Tale of the Tape
Interactive Investor (ii) is the UK’s primary flat-fee retail investment platform, supervising tens of billions in assets under the corporate umbrella of abrdn. It operates on a subscription software model: offering Core (£5.99/month for portfolios up to £100,000), Plus (£14.99/month for unlimited portfolios, including a SIPP, ISA, GIA, and up to five family members), and Premium (£39.99/month). It provides whole-of-market fund and equity trading, free regular monthly investing, and native multi-currency accounts.
AJ Bell (LSE: AJB) is a publicly traded investment platform managing over £85 billion across retail and advised channels. It utilizes a hybrid pricing model: charging a percentage fee (0.25%) on unit trusts/funds while strictly capping custody fees on exchange-traded instruments (shares, ETFs, investment trusts, and bonds). It caters to DIY investors seeking a full wrapper suite—including a Lifetime ISA (LISA)—low dealing commissions, and curated research via its in-house publication, Shares Magazine.
The Fine Print Reality Check
Marketing teams promote low platform fees, but long-term wealth compounding in the UK is dictated by the split between funds and shares, wrapper fee caps, SIPP pricing, and currency conversion mechanics:
- The Platform Fee Crossover Math (Funds vs. Shares/ETFs): On Mutual Funds (OEICs / Unit Trusts), AJ Bell charges 0.25% per year on the first £250,000, tapering to 0.10% up to £500,000. Interactive Investor charges a flat £5.99/month (£71.88/year) on Core and £14.99/month (£179.88/year) on Plus. The Breakeven: For a pure fund portfolio, AJ Bell’s 0.25% fee hits ii Core’s £71.88 floor at just £28,752. Once your fund portfolio exceeds £28,752, Interactive Investor is cheaper. On a £250,000 fund portfolio, AJ Bell charges £625 per year, while ii Plus charges £179.88 per year. On Shares and ETFs, AJ Bell caps custody charges: 0.25% capped at £42/year in an ISA, capped at £120/year in a SIPP, and £0 in a General Dealing Account. If you hold an ISA with £80,000 in a global index ETF, AJ Bell costs just £42/year, while ii Core costs £71.88/year.
- The Lifetime ISA (LISA) & Wrapper Architecture: AJ Bell offers a Lifetime ISA (LISA). If you are under 40 and saving for your first home or retirement, you can deposit up to £4,000 per tax year and claim an immediate 25% government bonus (up to £1,000/year). Share custody in the AJ Bell LISA is capped at £42/year. Interactive Investor does not offer a Lifetime ISA.
- The SIPP Pricing & Consolidation Structure: Interactive Investor includes the SIPP inside its unified subscription plans. You pay £5.99/month on Core or £14.99/month on Plus. Holding an ISA, SIPP, and GIA incurs zero additional wrapper surcharges. AJ Bell charges separate fees per wrapper: a SIPP holding funds pays 0.25% (up to £625/yr on £250k), while a SIPP holding shares/ETFs pays 0.25% capped at £120/year. If you hold both an ISA and a SIPP in pure ETFs, AJ Bell costs £162/year, roughly matching ii Plus.
- Trading Commissions & Regular Monthly Investing: Regular Investing: Both platforms offer free (£0) automated monthly regular investing. Discrete Order Tickets: AJ Bell charges £1.50 per deal on funds and £5.00 per deal on shares/ETFs (dropping to £3.50 with 10+ share deals). Interactive Investor (Core) trades cost £3.99 for funds and shares. On Plus, fund trades drop to £1.49, and you receive one free trade credit every month.
- Foreign Currency Accounts vs. Auto-FX Conversion Rakes: Interactive Investor provides a native multi-currency account within its Trading Account wrapper. You can hold balances across 9 foreign currencies. US dividends settle directly into your USD cash balance without forced currency conversion drag. FX conversion tiers start at 0.75%. AJ Bell is strictly a GBP-denominated platform. You cannot hold foreign currencies. All non-GBP dividends are automatically converted to sterling at a tiered FX fee (0.75% on the first £10,000).
- The Family Compounding Moat (ii Family Plan): Interactive Investor (Plus plan) allows you to add up to five family members with fee-free accounts included in your £14.99/month subscription. If you, your spouse, and two adult children each hold ISAs, ii covers all four accounts for a single combined fee of £179.88/year. AJ Bell charges each individual account holder their own independent platform fees.
The Fine Print Translation
Interactive Investor is a flat-fee subscription powerhouse: crushing percentage fees once a fund portfolio exceeds £29,000, bundling SIPP and ISA wrappers under a single £14.99/month fee, including family accounts, and offering multi-currency USD wallets. AJ Bell is a hybrid execution house: offering a 25% bonus Lifetime ISA, £0 custody on GIA shares, and a tight £42/year cap on ISA ETFs—beating ii for small-to-midsize pure ETF investors, but penalizing large mutual fund holdings with an uncapped 0.25% charge.
The Daily Driver Test
Your platform experience depends entirely on whether you want an all-in-one family subscription hub or a research-heavy broker with specialized retirement wrappers.
AJ Bell operates like a traditional British stockbroking institution updated for modern devices. The web portal and mobile app are structured, data-dense, and stable. Research is a major operational strength: every customer maintaining an account balance of £4,000+ receives a free digital subscription to Shares Magazine, alongside AJ Bell’s curated 'Favourite funds' lists and detailed market analysis. Setting up free regular investing or claiming a 25% LISA government bonus is completely seamless. The interface friction surfaces primarily when trading US shares, as mandatory automated FX conversions deduct a spread on every trade and dividend without allowing cash to remain in USD.
Interactive Investor operates like a clean, utility-first digital investment dashboard. Managing your ISA, GIA, and SIPP behind a single login feels cohesive, and adding family members to your subscription takes just a few clicks. Its Super 60 and ACE 40 rated fund lists provide clear starting points for fund allocators. For international equity investors, the multi-currency desktop portal is a standout: you can hold USD cash, set limit orders on US bourses, and receive quarterly dividend payouts without paying a forced 0.75% FX toll every time a dividend clears. However, ii offers no Lifetime ISA, and if your total portfolio is under £25,000, paying a flat subscription fee feels like an unnecessary monthly overhead.
The Wingwoman Allocation
Don’t pay an uncapped 0.25% on a six-figure fund portfolio out of habit, and don’t pay a flat £180 subscription if a £42 cap on AJ Bell covers your entire ETF book. Match your platform to your asset split, wrapper type, and portfolio balance:
- Deploy with Interactive Investor (ii) if: You hold a mutual fund (OEIC) portfolio exceeding £30,000, where ii’s flat fee saves you hundreds of pounds annually over AJ Bell’s 0.25% charge. You have a six-figure consolidated balance across multiple wrappers (ISA + SIPP + GIA), capturing ii’s single £14.99/month Plus plan without paying separate wrapper custody fees. You want to exploit the ii Family Plan, extending fee-free ISA and investment accounts to your spouse and children under your single Plus subscription. You actively invest in US-listed equities and dividend payers, utilizing ii’s multi-currency wallets to hold USD. Your portfolio balance is between £30,000 and £100,000, unlocking the streamlined Core plan at £5.99/month.
- Deploy with AJ Bell if: You are eligible for and want to utilize a Lifetime ISA (LISA) to capture the 25% government bonus for first-time home buying or retirement. You invest exclusively in ETFs, investment trusts, or UK shares inside an ISA, locking in AJ Bell’s £42/year custody cap to beat ii’s subscription cost. You hold shares or ETFs in an unwrapped General Investment Account (GIA), taking advantage of AJ Bell’s £0 share custody fee. Your total investment pot across all wrappers is under £28,000, where AJ Bell’s 0.25% percentage fee works out cheaper than ii’s £71.88 base floor. You value direct access to high-grade UK market commentary and a complimentary subscription to Shares Magazine.
Your Wingwoman Move
If you are building wealth through ETFs, investment trusts, and single stocks in an ISA or GIA, AJ Bell is the mathematical winner. Capping your annual ISA platform fee at £42/year and paying £0 custody on GIA shares undercuts Interactive Investor's subscription fee while providing access to a Lifetime ISA.
However, the moment your portfolio transitions into substantial mutual funds (OEICs) or you hold a combined six-figure ISA and SIPP balance, AJ Bell’s 0.25% uncapped fund fee becomes an expensive drag. Consolidate those balances into Interactive Investor Plus (£14.99/month): you will cap your entire family's platform costs at £179.88/year, eliminate percentage drag on funds, unlock multi-currency USD dividend holding, and keep hundreds of pounds compounding on your balance sheet.
Use the capped specialist for pure ETF and LISA compounding, and use the flat-fee subscription engine when multi-wrapper scale and fund balances take over. Go get paid.