Negotiable Instruments Act Section 20 — Inchoate stamped instruments
CHAPTER II OF NOTES, BILLSAND CHEQUES
General
Summary
If you sign and hand over a stamped paper that is either blank or only partially filled in, you give the person holding it the basic authority to turn it into a complete negotiable instrument, as long as the amount filled in does not go beyond what the stamp covers. You become liable on that instrument in the same role you signed it for, but only to someone who receives it in good faith and for value (a holder in due course). If the person who receives it is not a holder in due course, they cannot recover more from you than the amount you actually intended to be paid.
Official Text
Where one person signs and delivers to another a paper stamped in accordance with the law relating to negotiable instruments then in force in 2[India], and either wholly blank or having written thereon an incomplete negotiable instrument, he thereby gives prima facie authority to the holder thereof to make or complete, as the case may be, upon it a negotiable instrument, for any amount specified therein and not exceeding the amount covered by the stamp. The person so signing shall be liable upon such instrument, in the capacity in which he signed the same, to any holder in due course for such amount: provided that no person other than a holder in due course shall recover from the person delivering the instrument anything in excess of the amount intended by him to be paid thereunder.