Section 28 of the Court-fees Act, 1870 deals with:

Section 28 deals with documents received by inadvertence without proper stamps: a document that ought to bear a stamp has no validity until stamped, but the judge or head of office may order it stamped if it was received by mistake or inadvertence. Renewal of spoiled stamps is a rule-making matter under s.27, cancellation is s.30, and refund on a review application is s.14.