11(1)A person who makes a return under paragraph 8 or 9 may amend that return by notice to an officer of Revenue and Customs.
(2)An amendment under sub-paragraph (1) may not be made more than twelve months after the end of the period in which the return must be delivered (see paragraphs 8(1) and 9(5)).
(3)An officer of Revenue and Customs may amend a return under paragraph 8 or 9 so as to correct—
(a)obvious errors or omissions in the return (whether errors of principle, arithmetical mistakes or otherwise), and
(b)anything else in the return that the officer has reason to believe is incorrect in the light of information available to the officer.
(4)A correction under sub-paragraph (3) is made by notice to the person whose return it is.
(5)No such correction may be made more than nine months after—
(a)the day on which the return was delivered, or
(b)if the correction is required in consequence of an amendment of the return under sub-paragraph (1), the day on which that amendment was made.
(6)A correction under sub-paragraph (3) is of no effect if the person whose return it is gives notice rejecting the correction.
(7)A notice under sub-paragraph (6) must be given—
(a)to the officer who gave the notice under sub-paragraph (4), and
(b)before the end of the period of 30 days beginning with the day on which the notice under sub-paragraph (4) was issued.