Section 123DPower of Commissioner regarding assessment

make, suo motu, an assessment in any case where a return on the basis of self-assessment has not been filed;

[Provided that no such assessment for an assessment year shall be made after the lapse of seven years from the close of that assessment year.] [(b) revise any assessment where the information furnished in the return of self-assessment is found to be incorrect or reopen any assessment where it has been detected that there is wilful suppression of information; and] [(c)] impose a penalty not exceeding thirty per cent of the difference in tax arising from non-filing of a return in time, giving wrong information or wilful suppression of facts.