Antedate – to give a document an earlier date than on which the document was executed (i.e. to backdate a document). This concept is reflective of the expression nunc pro tunc (“now for then”) whereby a judgment or order made by a Court can have retrospective effect (i.e. having the same legal force and effect as if it had been entered on an earlier date). This concept is a product of Australia’s common law heritage and the general power of the Court to back date any order is elucidated in Hartley v Poynton Ltd v Ali  VSCA 53. In this case an order of the Court was backdated so that interest on a judgment would be calculated as at the date a decision of the primary Court was made, rather than at the date of the decision of the Court of Appeal.
Along with orders and judgments of a Court, documents themselves can be antedated. The most common types of documents that are antedated are contracts. When this occurs, a contract’s effective date is prior to the date of the contract being executed. An example of a type of contract that may be back dated is an oral lease agreement that is subsequently transposed into a written instrument and deemed to have taken effect as at the date of the oral agreement.
There are circumstances whereby antedated a document may amount to fraud and/or a misrepresentation. This will be dependent upon case by case analysis. It is important to note that although the backdating of an invoice, bill or cheque may amount to evidence of a fraud and/or misrepresentation, it in and of itself will not be enough to invalidate the document (see s 16 (b) of the Cheques Act 1986 (Cth).