21.—(1) A claimant is to be treated as having limited capability for work on any day on which that claimant is undergoing medical or other treatment as a patient in a hospital or similar institution, or on any day which is a day of recovery from that treatment.
(2) The circumstances in which a claimant is to be regarded as undergoing treatment falling within paragraph (1) include where the claimant is attending a residential programme of rehabilitation for the treatment of drug or alcohol addiction.
(3) For the purposes of this regulation, a claimant is to be regarded as undergoing treatment as a patient in a hospital or similar institution only if that claimant has been advised by a health care professional to stay for a period of 24 hours or longer following medical or other treatment.
(4) For the purposes of this regulation, “day of recovery” means a day on which a claimant is recovering from treatment as a patient in a hospital or similar institution as referred to in paragraph (1) and the Department is satisfied that the claimant should be treated as having limited capability for work on that day.