Section 100 of Stamp Duty Act CAP 480: Allowance for misused stamps

Where a person has inadvertently used for an instrument liable to duty a stamp of sufficient amount but of improper description, or a stamp of greater value than was necessary, or has inadvertently used a stamp for an instrument not liable to any duty, a collector may, on application made within one year after the
date of the instrument, or, if it is not dated, within six months after the execution thereof by the person by whom it was first or alone executed, and upon the instrument, if liable to duty, being stamped with the proper duty, and subject to the provisions of section 21, cancel and allow as spoiled the stamp so misused.