The Bank of England temporarily increased the capital requirements for Monzo as the challenger bank looked to raise funds earlier this year, according to the Financial Times.
In May, Monzo was required to have capital worth of 13.65% of risk-weighted assets, up from about nine per cent, as well as a fixed amount of £21 million, says the FT.
The hike - which meant Monzo's capital requirements were briefly twice as high as some high street banks - comes after the BoE pledged to strengthen capital planning at small banks.
In June, Monzo was forced to take a 40% discount on a £60 million funding round. The FT notes documents circulated by an investor in May said the bank needed at least £20 million to avoid breaching regulatory requirements.