"The personal capacity assessment (PCA) is the main medical test for people who claim incapacity benefit. It "sets a threshold of incapacity that must be met as one of the conditions of entitlement to benefit". The majority of claimants will be subjected to the assessment after the first 28 weeks of incapacity.

The process starts with the claimant being asked to complete a questionnaire (ref IB50) and the claimant's gp being asked to complete a form (MED 4) setting out the claimant's condition and its disabling effects.

Once the DWP decision maker has received both completed forms, he will decide whether or not to seek a further medical opinion from an approved doctor. The DWP's leaflet on the PCA states- " Given the wide variability of effects of medical conditions between individuals, the majority of cases will be referred for a medical opinion from an approved doctor." The doctor may be able to give sufficent advice from the written evidence or may feel that further information is needed from the claimant's doctor or that a medical examination is required...."

Source:
http://benefitsnow.co.uk/incapacity/personalcapacity.asp