17.—(1) The categories of exempt work referred to in regulation 16(1)(a) are—
(a)work undertaken on the advice of a doctor which—
(i)helps to improve, or to prevent or delay deterioration in, the disease or bodily or mental disablement which causes that person’s incapacity for work; or
(ii)is part of a treatment programme and is done under medical supervision while that person is an in-patient or regularly attending as an out-patient of a hospital or similar institution; or
(iii)is done while that person is attending an institution which provides sheltered work for people with disabilities;
(b)work done as a volunteer;
(c)duties undertaken as a member of a disability appeal tribunal or the Disability Living Allowance Advisory Board.
(2) The weekly limits in relation to exempt work are—
(a)that earnings from work referred to in paragraph (1)(a) do not exceed £43;
(b)that, subject to paragraph (3), the combined total of the number of hours spent doing work referred to in paragraph (1)(a)(i) or (b) is less than 16;
(c)that work referred to in paragraph (1)(c) is not undertaken on more than one day.
(3) A person shall not be treated as capable of work because he has exceeded the limit referred to in paragraph (2)(b) in any week, if he has worked or would be expected to work, as the case may be, an average of less than 16 hours a week—
(a)in a case where a recognisable cycle in respect of that person’s work has been established, in the period of that cycle in which the week in question falls; or
(b)in any other case, in the period which comprises that week and the 4 weeks preceding it.