If elected, your term of office as the Mayor of London or as an Assembly Member will become effective on the second calendar day after the day on which the last of the successful candidates at an ordinary election is declared returned.
However, you may not act as Mayor of London or as an Assembly Member (this includes attending and voting at meetings) until you have made the declaration of acceptance of office and delivered it to the Proper Officer of the Greater London Authority (GLA).1
The declaration must be made within two months from the day of election.2
If you do not submit your declaration by this deadline, the seat will be declared vacant and a by-election will be held, unless you are a London-wide Assembly Member who was elected on a party list, in which case the next person on the party list would be deemed to be elected.
The GLA will provide candidates with guidance on the declarations process and requirements.