Section 40: l11~lJ wncnts ttwluly stamped T>!J acczdr.:nt

If any instrument_ char­ geable with duty and not duly stamped, not being an instrument chargeable with a duty of twelve naye paic;e or less is produ­ ced by any person of his own motion before the Collector Within one year from the date of its execution or first execution and such person brings to the notice of the Collector the fact that such instrument is not duly stamped and offers to pay to the Collector the amount of the proper duty, or the amount required to m1ke up the same and the Collector is satisfied that the omission to duly stamp such instrument has been occasioned by accident, mistake or urgent necessity, he may, instead of proceeding under sections 33 and 39, receive such amount and proceed as next hereinafter prescribed.