As per Section 12 of the Indian Stamp Act, 1899, what must a person do immediately after affixing an adhesive stamp to an instrument chargeable with duty?

Section 12 of the Indian Stamp Act, 1899 requires that whoever affixes an adhesive stamp to an instrument chargeable with duty must cancel it at the time of affixing, ensuring the same stamp cannot be reused on another document. This cancellation can be done in any effectual manner, such as writing one's name, initials, or the firm's name across the stamp along with the true date, though any method that permanently defaces the stamp is acceptable. Section 12(2) adds an important consequence: if an adhesive stamp on an instrument is not properly cancelled, the instrument is treated as if it were unstamped altogether, regardless of the stamp's physical presence on the paper. Section 11 specifies which categories of instruments may actually be stamped using adhesive stamps, including bills of exchange or promissory notes drawn outside India, notarial acts, entries of advocates on a High Court roll, and share transfers by endorsement. Failure to cancel an adhesive stamp as required attracts a penalty under Section 63, reinforcing why this seemingly minor procedural step carries real legal consequences for the instrument's validity.