The system for assessing disability benefits has "serious failings", according to a committee of MPs.
Claimants were not receiving an "acceptable level of service" and the cost to the taxpayer of paying private firms to carry out the assessments was set to double to £579 million in 2016-17, according to the Public Accounts Committee.
- evidence of "arduous journey times"
- double booked appointments
- assessments overturned on appeal
- some assessors "do not understand particular medical conditions"
- up to one in five reports sampled were "below the required standard"
The Commons spending watchdog said that the Department for Work and Pensions (DWP) and its private contractors were making progress to reduce delays and improve the quality of assessments but the regime still fell short of expectations.
Subsidiaries of Maximus are responsible for the Employment and Support Allowance (ESA) and Fit for Work service, while Atos and Capita carry out Personal Independence Payment (PIP).
The committee said: "Claimants are still not receiving an acceptable level of service from contractors, with particular concerns for claimants with fluctuating and mental health conditions."
The average time for PIP contractors to return assessments to the DWP was an "acceptable" four weeks, while ESA assessments took 23 weeks on average.
The committee heard concerns from mental health charity Mind, Citizens Advice and the Disability Benefits Consortium about claimants' "poor" experiences.
The MPs also noted that contractors were not required to employ doctors to carry out health and disability assessments, instead relying on practitioners including nurses and occupational therapists.
Only Maximus - with 186 doctors within its workforce of 1,251 - recruits doctors to conduct assessments, the report said.