20.—(1) If the code for use by an employer in respect of an employee is amended after notice of it has been issued to the employer, the Inland Revenue must issue the amended code to the employer.
(2) An amended code is issued to an employer if it is contained in a document that is sent to the employer or a person acting on behalf of the employer by the Inland Revenue, and any code so issued is received by the employer for the purposes of these Regulations.
(3) On making any subsequent relevant payment to the employee, the employer must deduct or repay tax by reference to the amended code.
(4) Paragraphs (5) and (6) apply if there is a change or proposed change in the rates of any of the personal reliefs allowable under sections 257 and 257A of ICTA (personal allowance and married couple’s allowance).
(5) If the change or proposed change relates to the current tax year, the Inland Revenue may give notice requiring the employer, with effect from the date specified in the notice, to amend specified codes as directed.
(6) If the change relates to the following tax year, the Inland Revenue may give notice requiring the employer to carry forward to the following tax year specified codes of the current tax year and adjust them as directed in the notice.
(7) A code which has—
(a)been amended by virtue of paragraph (5) in respect of the current tax year, or
(b)been carried forward to the following tax year and adjusted by virtue of paragraph (6),
is treated as having been determined and issued by the Inland Revenue as the employee’s code for that tax year.
(8) A notice under paragraphs (5) and (6) may be issued to the employer or to a person acting on behalf of the employer.