Fidelity’s ‘Price Promise’, which runs until 31 December 2014 for investors with under £1m in assets, will come into force if investors find cheaper funds on four platforms: Hargreaves, Barclays, Bestinvest and TD Investing.

The offer applies to investments in ‘clean share classes’ on its Personal Investing platform.

Fidelity suggested the move is designed to remove the focus on price from the investment decision-making process.

The move will “enable investors to find the right funds for their needs without having to worry about which of the leading platforms is currently offering the best deal on their choice of funds”, according to Mark Till, head of Fidelity Personal Investing.

Fidelity has already announced a competitive annual charge for users of its DIY platform, introducing an annual management charge of 0.35% for clients with total assets up to £250,000.

The price undercut rival Hargreaves, which is charging 0.45% for that price bracket.

Customers will be able to claim their refunds between 1 January and 28 February 2015 online, and between 1 January and 15 March 2015 for paper claims.