Assumptions
What this page models
- £20,000 current balance
- Investment type set to index or mutual funds
- No monthly contribution, so no annual trades are modelled
- No US-stock FX assumption
This page is deliberately narrow. It is not trying to name the best ISA; it answers a fee question: what does the platform wrapper cost for a £20,000 index fund ISA?
Providers that do not support open-ended funds are excluded unless the calculator says the holding would need to move into ETFs. Fund ongoing charges are excluded because they belong to the fund, not the ISA platform.
Educational fee comparison only. This is not financial advice, tax advice, or a recommendation to use any provider. Fees, eligibility, investment access, and promotions change; verify the current provider fee schedule before opening or transferring an ISA.