Demand under Section 73: recovery process and penalty for non-payment after show cause notice issued Where tax is unpaid, short paid, erroneously refunded, or input tax credit wrongly availed or utilised for reasons other than fraud or willful misstatement, the proper officer shall serve a notice and adjudicate; a show cause notice must be issued at least three months before an order and orders are generally issued within three years from the due date for the relevant annual return (with specified extensions). A statement served after an earlier notice on the same grounds is deemed a notice. Voluntary payment with interest prevents notice for the paid amount, but short payments permit issuance of notice; payment within thirty days of a show cause notice avoids penalty, whereas non-payment within thirty days of the due date attracts a statutory penalty.