21.—(1) Subject to paragraphs (2) and (3), the information or evidence required to determine whether a claimant has limited capability for work is—
(a)evidence of limited capability for work in accordance with the Medical Evidence Regulations (which prescribe the form of doctor’s statement or other evidence required in each case);
(b)any information relating to a claimant’s capability to perform the activities referred to in Schedule 2 as may be requested in the form of a questionnaire; and
(c)any such additional information as may be requested.
(2) Where the Department is satisfied that there is sufficient information to determine whether a claimant has limited capability for work without the information specified in paragraph (1)(b), that information shall not be required for the purposes of making the determination.
(3) Paragraph (1) does not apply in relation to a determination whether a claimant is to be treated as having limited capability for work in accordance with regulation 20, 25, 26 or 33(2).