The cost of appeals against decisions on whether people are fit to work was more than £25mn in the first half of 2012, peers have been told during question time in the Lords.
Welfare Reform Minister Lord Freud said Atos, the firm in charge of carrying out work capability assessments, conducted on average 100,000 assessments per month.
He said appeals against the decisions had cost the Work and Pensions Department £11.3mn, and the courts £14.9mn.
The minister revealed the figures on 26 November 2012 after Labour peer Baroness Wilkins told the Lords that 40% of people who had appealed had been successful.
Responding to Lady Wilkins's comment, Lord Freud said: "In total that figure is roughly accurate - 40% of those who go to appeal.
"Of the total number of those found fit to work, the tribunal only changes around 15% of that total and the reasons are usually to do with fresh evidence either written or oral."
Lord German, a Liberal Democrat peer, expressed concern that one in four Atos centres "did not have flat level access" for wheelchairs.
He asked the government whether it could ensure that all people who need wheelchair access would have have access to these centres.
Lord Freud said 31 of the assessment centres were not on the ground floor and lifts had to be used.
"The issue then arises that if there is an emergency - a fire emergency for instance - those people will have to go down the stairs, which is obviously not satisfactory.
"To the extent that people are concerned about that - either they are visited on the ground floor or somewhere else or, indeed, at home."
Other questions to the government covered vocational education, apprenticeships for young people with special educational needs and the UK's future role in the EU.