An officer of the Board may amend a return under section 8 or 8A of this Act 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.
A correction under this section is made by notice to the person whose return it is.
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 section 9ZA of this Act, the day on which that amendment was made.
A correction under this section is of no effect if the person whose return it is gives notice rejecting the correction.
Notice of rejection under subsection (4) above must be given—
(a) to the officer of the Board by whom the notice of correction was given,
(b) before the end of the period of 30 days beginning with the date of issue of the notice of correction.