One balance, two ways to hold it
AJ Bell's ISA tariff charges 0.25% a year on shares (including ETFs, investment trusts and gilts), capped at £3.50 a month; its funds (unit trusts and OEICs) cost 0.25% on the first £250,000, 0.10% on the next £250,000 and zero on the remainder. Those are separate charges on separate holdings. The provider's own £30,200 mixed-portfolio example bills £2.50 a month for £12,000 of shares plus £3.75 a month for £18,000 of funds. The £42 cap does not shelter the fund portion.
Vanguard's self-managed ISA tariff charges £4 a month if the invested balance across accounts is under £32,000, or 0.15% annually from £32,000, capped at £375. This applies to its own funds and ETFs; it does not offer individual company shares or third-party funds. For the matched example, take either the same Vanguard ETF at both providers or the same Vanguard mutual fund at both providers; do not compare an ETF's platform bill with a fund's investment performance. At £40,000 and with £200 added monthly, the account remains above Vanguard's £32,000 threshold if markets do not move.
The chart shows cumulative estimated custody fees in pounds for five years: £40,000 invested at the start, twelve £200 month-end additions per year, no withdrawals or trades beyond the monthly purchases, and zero market return. Annual charges are approximated using the average of the twelve month-end balances. AJ Bell ETF charges are at the monthly cap throughout. Vanguard's 0.15% and AJ Bell's fund 0.25% are applied to those average balances. Monthly dealing via AJ Bell's eligible regular investing service is free; fund OCFs, spreads and any ad-hoc dealing are excluded because they depend on the investment and how you trade.
What changes the recommendation? At this balance, the £366.25 gap between AJ Bell's fund bill and its ETF bill over five years is larger than the £135.75 ETF-platform advantage over Vanguard. Switching the holding to chase a custody cap brings spread, possible dealing charges and differences in fund tracking and structure into the decision; compare the actual ETF and fund documents before doing so. Our platform directory and AJ Bell core review cover features beyond fees.