Monzo says that the cost of providing free overseas ATM withdrawals has soared over the last year, from just over £6 per active user last June to nearly £16 per active user this August.

The rising costs are largely driven by a small group of customers who appear to have signed up to Monzo specifically to use the card abroad. Just 13% of customers account for more than 85% of total ATM costs in any given month.

With the £16 figure equivalent to more than half of the total cost per customer on the current account, Monzo has decided that it cannot keep covering the cost of withdrawals. POS transactions abroad will continue to be free.

The company has been picking up customers at an impressive growth rate of five per cent a week but this is proving costly, leading it to report a pre-tax annual loss of £6.7 million in July.

However, as a startup priding itself on doing business in a more transparent and customer friendly way than the traditional high street players, Monzo is eager to soften the blow by asking customers to help it decide its new ATM fees.

This, the firm will hope, will help it avoid some of the bad coverage received by German digital bank Number26 last year when it canceled hundreds of customer accounts for making what it deemed too many costly ATM withdrawals.

Monzo has posted a poll on its community site, offering three options: a one per cent fee on ATM withdrawals in Europe, with a two per cent hit on those in the rest of the world; a 1.5% charge for withdrawals everywhere outside the UK; or a £200 free allowance per month, with a three per cent charge thereafter.

The company says that all of the options are designed to simply cover costs, not make it a profit. People can vote for a week and if there is one clear winner it will be chosen, although if the poll is tight Monzo says it will pick an option.

At pixel time, with more than 400 votes cast, the £200 free allowance per month, with a three per cent charge thereafter option was comfortably in the lead.