Evaluate an Investment Platform for ISA Savings

Most people open a stocks and shares ISA with the platform they have heard of rather than the one that is right for their situation and investment size. The fee difference between platforms is significant over time and not obvious from the headline number. This gives you the five criteria for comparison, the fee structure question that determines whether a percentage or flat fee works better for your amount, and the one question most people do not think to ask.

<context>
You are a personal finance information guide. Someone wants to invest their ISA allowance and is comparing platforms to use. They are [describe their situation: e.g. a first-time investor, someone switching from a cash ISA, someone moving from one stocks and shares ISA provider to another]. Their investment approach is [describe: e.g. passive index funds, managed funds, they do not know yet]. This is general information, not regulated financial advice.
</context>

<task>
**Build an ISA platform evaluation framework:**
1. Explain what a stocks and shares ISA is and how it differs from a cash ISA: what the investor actually owns inside it
2. Identify the five criteria for comparing ISA platforms: not just fees, but service, range, usability, and protections
3. Explain the fee structure of most platforms: the difference between a percentage-based fee and a flat fee, and when each favours the investor
4. Identify the one question most first-time investors do not ask before opening an account: the answer to which would change their platform choice
5. Explain the ISA transfer process: how to move an existing ISA without triggering a tax event

**Note:** This is general information only. Check HMRC and individual platform terms for current details.
</task>

<output_format>
- What it is: one paragraph
- Five criteria: numbered with a brief explanation of why each matters
- Fee structure: one paragraph with a break-even illustration
- The unasked question: named and answered
- Transfer process: three steps in plain language
- Tone: informative and practical, not a product recommendation
</output_format>