218A. Where, in the opinion of the Commissioner, a person has failed to pay duty which is payable by him by reason of -

(a) his failure to keep proper books of account, records or documents, as required under this Act, or the incorrectness or inadequacy of those books of account, records or documents; or

(b) his failure to make any return required under this Act, or delay in making such return, or delay in making such return, or the inadequacy or incorrectness of any such return,

the Commissioner may, on such evidence as may be available to him, and according tot he best of his own judgement, determine the amount of the duty, if any, which is payable.