To help you see how much platform and fund charges are eating into your annual profit, use the Telegraph Money calculator below. Investors typically pay a “platform” fee – a charge levied by a stockbroker, such as Interactive Investor – as well as a fund fee charged by the investment company deciding where you cash is invested. How much will investment fees cost you? It’s not uncommon to be charged fees of 1pc, which might sound pretty cheap on the face of it. The same investment with a fairly cheap platform fee of 0.3pc, and fund charges of 0.11pc – the average charged by index trackers – would leave you with £193,130.50.