Chancellor Rachel Reeves is being investigated by Parliament's standards watchdog after failing to declare on time that she received free theatre tickets.
It is understood the chancellor attended an event at the National Theatre over Christmas but did not add the donation to the MPs' register of interests within the specified timeframe.
The BBC has been told Reeves did declare the trip on her ministerial register, which is separate from the MPs' register. The parliamentary code of conduct states that MPs must register their financial interests and update any changes within 28 days.
