Cancellation of firm registration: authority may cancel and re-assess firm and partners on an unregistered footing after notice. Where the assessing authority is satisfied that a registered firm was not a genuine firm or has committed specified failures, it may cancel the firm's registration after giving notice and a reasonable opportunity to be heard. Cancellation leads to amendment of the assessments of the firm and its partners on the footing that the firm is an unregistered firm, with amendments governed by section 154 procedural rules and the limitation period reckoned from the end of the financial year in which the cancellation order was passed. A temporal bar limits cancellation after a prescribed number of years.