Ussher allegedly switched her designated primary home from London to Burnley for one month in order to avoid paying £16,800 in CGT when she sold her constituency home in 2007.
In Brown’s cabinet reshuffle two weeks ago, Ussher was moved from the Department of Work and Pensions to the Treasury.
Ussher says she did not do anything wrong but in her resignation letter she said she was leaving because she did not want to cause the Government any embarrassment.
She announced yesterday that she would be standing down from her Burnley seat at the next general election and said this was because she wanted to spend more time with her family.
Department for Communities and Local Government minister Sarah McCarthy-Fry will replace Ussher at the Treasury.