Dr Gibson says he was harshly treated
The date for the Norwich North by-election, triggered by the resignation of Labour MP Ian Gibson, has been set for 23 July.
Dr Gibson quit after Labour officials said he could not stand at the next election following criticism of his expenses claims.
One of five Labour MPs deselected by the party over their expenses, Dr Gibson said he was harshly treated.
He had a majority of just over 5,000 at the last election.
The writ for the election sets the poll date two days after Parliament breaks up for its summer recess on 21 July.
The seat will be a target for the Tories and should be a pointer to how Labour may fare in key constituencies in the south of England at the next general election.
Despite recent speculation about his intentions, Dr Gibson told BBC Look East that he would not be standing as an independent candidate.
The MP, who was alleged to have allowed his daughter to live in his taxpayer-funded second home and then sold it to her at below market value, has held the seat since 1997.