23.—(1) Subject to regulation 24 (applications: universal credit claimants) and regulation 25 (telephone applications) an application must be sent in writing to the office designated by the relevant authority as the office to which applications should be sent and—
(a)made on a properly completed form approved for the purposes by the relevant authority, or
(b)in such written form as the relevant authority accepts as sufficient in the circumstances of any particular case or class of cases having regard to the sufficiency of the written information and evidence.
(2) Where an application is not made in the form described in paragraph (1)(a) or (b) it is defective.
(3) Where an application is defective because—
(a)it was made on the form approved for the purpose but that form is not accepted by the relevant authority as being properly completed, the relevant authority may request the applicant to complete the defective application, or
(b)it was made in writing but not on the form approved for the purpose and the relevant authority does not accept the application as being in a written form which is sufficient in the circumstances of the case, having regard to the sufficiency of the written information and evidence, the relevant authority may supply the applicant with the approved form or request further information or evidence.
(4) A defective application is to be treated as if it had been validly made in the first instance if, in any particular case, one of the conditions specified in paragraph (5) is satisfied.
(5) The conditions are that—
(a)where paragraph (3)(a) (incomplete form) applies, the relevant authority receives the properly completed application or the information requested to complete it within one month of the authority’s request, or any longer period the relevant authority considers reasonable, or
(b)where paragraph (3)(b) (application not on approved form or further information requested by relevant authority) applies—
(i)the approved form sent to the applicant is received by the relevant authority properly completed within one month of it having been sent to the applicant, or any longer period the relevant authority considers reasonable, or
(ii)the applicant supplies whatever information or evidence was requested under that paragraph within one month of the request, or any longer period the relevant authority considers reasonable.
(6) An application made on an approved form is for the purposes of these Regulations properly completed if completed in accordance with the instructions on the form, including any instructions to provide information and evidence in connection with the application.