Boris Johnson has returned his questionnaire about allegations of Downing Street lockdown breaches to the police.
The PM was one of more than 50 people to be sent the document by the Metropolitan Police, which is looking at potential Covid rule-breaking.
Mr Johnson had until 22:00 GMT on Friday to answer the survey.
He has said he did not believe he was breaking any rules, but apologised “for the things we simply didn’t get right”.
Mr Johnson has received legal advice about his response.
The Met has said a fine would be issued to anyone found to have breached Covid regulations. A decision is not expected for weeks.
The force previously said the questionnaires would ask what had happened and “must be answered truthfully”.
The documents, which were sent by email, require an “account and explanation of the recipient’s participation in an event”, the Met said.
But it added that being contacted did not mean a fine would always be issued.
The questionnaire has the same status as information given in an interview under caution.
The police investigation was launched in late January after an internal inquiry led by civil servant Sue Gray passed information to the force.
Detectives investigating the parties have been handed more than 500 documents and 300 images gathered as part of Ms Gray’s inquiry.
The initial findings of Ms Gray’s inquiry criticised “failures of leadership and judgement” over the gatherings in Downing Street and Whitehall.