Is is not clear whether Ms Josephs has received a fine.
Ms Josephs was the head of the Covid Taskforce, and responsible for writing the lockdown rules.
At the time of the event, people in London were banned from socialising indoors away from their household or support bubble.
Shortly before details of the event were first made public in January, Ms Josephs said she was “truly sorry” for what had happened.
In a statement posted on Twitter, she said: “On the evening of 17 December, I gathered with colleagues that were at work that day with drinks in our office in the Cabinet Office to mark my leaving the civil service.
“I am truly sorry that I did this and for the anger that people will feel as a result.
“Sheffield has suffered greatly during this pandemic, and I apologise unreservedly.”