By bizn_fun 
“For a short period today, we activated Monzo Stand-in – our fully independent backup bank – while we investigated an issue,” they told the BBC.
“Customers were always able to make payments with their card, withdraw cash, freeze their card and send and receive bank transfers.”
Many attempting to open the app after 15:00 GMT on Tuesday were met with a notice telling them “we’re experiencing issues”.
This said the app would not function as normal but other services, such as viewing account details and moving money between accounts, would be available.
However, some users attempting to access the app took to social media to complain to Monzo that they could not view funds, recent payments or make bank transfers.
In posts seen by the BBC, some X users also told Monzo they had been unable to use their card or withdraw money.
The BBC has asked Monzo for comment about these complaints.
The company has more than 14 million personal and business customers across the UK.
It has previously highlighted its back-up banking infrastructure as a way it avoids large-scale outages and issues for customers – many of which were seen across other UK banks during a spate of online outages last year.
About 1.2m people in the UK were affected by banking outages occurring on what was pay day for many in early 2025.