Birmingham's newest MP will stay on as a city councillor until May 2016 - saying she will save the taxpayers the cost and inconvenience of another by-election.
But Jess Phillips, who became Labour MP for Yardley last month, has been accused by her predecessor, Lib Dem John Hemming, of breaking a campaign pledge to be a full-time MP.
But Ms Phillips hit back by pointing out that Mr Hemming remained a councillor for three years after being elected to Parliament in 2005.
READ MORE: {}
Her term as councillor for Longbridge is due to expire next May and the new MP has confirmed she will step aside then - rather than call a by-election to choose a councillor for a few months.
Birmingham councillors are paid a basic allowance of £16,267 a year while an MP's basic salary is £67,060. The cost of a council by-election is £25,000.
Mr Hemming said that, during the election campaign, "Jess Phillips criticised me for representing Yardley as MP and South Yardley as a councillor".
"This involved going to the same meetings with two hats on," he said.
"She also pledged to resign her council seat 'unlike John Hemming'.
Most Read
"However, now the election is over she is pocketing the £16,000 councillor expenses and has reneged on her pledge to be 'full time MP for Birmingham Yardley'. She is undermining trust in politicians."
Mr Hemming said he used his councillor's allowance to pay for extra services.
But Ms Phillips hit back saying it was a "bit rich" for Mr Hemming to criticise as he remained a councillor until 2008.
In the meantime, she says she will carry out her duties in Longbridge such as holding surgeries and attending ward committees as they take place on Fridays and weekends when she is in Birmingham.
Ms Phillips said: "If we called a by-election now, it would cost the taxpayer to run it and the person elected would be up for re-election next May anyway.
"In the meantime, I will be doing my share of casework and attending local committee meetings."