A by-election will be held in Ealing's Northfield ward after the resignation of Conservative Councillor Mark Reen.
The by-election will be held on the same day as the parliamentary election - Thursday May 7.
Voters living within the ward will be given two polling cards – one for the parliamentary election and one to elect a third councillor to represent them on Ealing Council.
People wishing to stand for election will need to declare their candidacy by 4pm on Thursday April 9.
A Notice of Election has been posted outside Ealing Town Hall and on the council’s website.
Residents have until Monday April 20 to register their details in time to vote.
Councillor Mark Reen said: “I have served the residents of Northfields for nine years as a local resident, but unfortunately my work commitments have changed meaning that work is now taking me out of London more frequently.
"Unlike some councillors who do not do their job and still claim their allowances I do not feel that it’s fair to claim mine.
"I hope that the residents recognise the work done by the Conservatives in the area who have been working on their behalf. I hope they will re-elect a conservative in the by-election given my resignation."
Until recently, every household was asked to register to vote on one form with one adult taking responsibility for returning information for all the eligible people at one address.
Now, as part of the national move towards an individual electoral registration (IER) system, everyone eligible to vote will have to register individually, across the country.
IER is being used in a bid to cut down on electoral fraud and to increase confidence in the system.
Most residents who are currently registered to vote will be registered automatically under the new system but some will need to re-register and others will need to check their details.
People who are not on the electoral roll will receive information on how to register to vote.
Visit www.ealing.gov.uk/vote2015 for more information.