A promissory note is a debt document characterised by particularly strong formal rigour. Even a slight deficiency can make it totally useless. In keeping with the provision of Article 33 of the Act of 28 April 1936—Promissory Note Law, a promissory note may be payable at sight, some time after sight, some time after a date or on a set day. At the same time, promissory notes with other payment deadlines or with multiple consecutive deadlines are null and void. Hence, one should be exceptionally diligent while receiving promissory notes.