The Employment Appeal Tribunal in The Commissioners for HMRC v Whiteley has suggested two approaches an employer can take where an employee’s disability interacts with other ordinary ailments in relation to sick absence.

Employers could look to determine precisely the level of absence that is attributable to a disability and what was not. Alternatively, an employer could ask and answer with proper information the question: ‘What sort of periods of absence would someone suffering from the disability reasonably be expected to have over the course of an average year due to the disability?’