(a) For the purpose of making an assessment on a chargeable person for a chargeable period or for the purpose of amending such an assessment, the inspector -
(i) may accept either in whole or in part any statement or other particular contained in a return delivered by the chargeable person for that chargeable period, and
(ii) may assess any amount of income, profits or gains or, as respects capital gains tax, chargeable gains, or allow any deduction, allowance or relief by reference to such statement or particular.
(b) The making of an assessment or the amendment of an assessment by reference to any statement or particular referred to in paragraph (a)(i) shall not preclude the inspector -
(i) from making such enquiries or taking such actions within his or her powers as he or she considers necessary to satisfy himself or herself as to the accuracy or otherwise of that statement or particular, and
(ii) subject to section 955(2), from amending or further amending an assessment in