Gaap backdating checks
However, such doctrines are normally limited to situations where one party backdates the contract without the knowledge or consent of the other.
Where both parties consent to the backdating of the document, normally the courts in common law countries will simply disregard the backdating of the document, and treat the rights as accruing from the date when the document was actually executed.
Probably the most difficult of the grey areas occurs where parties have a recurring commercial relationship which starts informally, but they later decide to document it and agree terms.
In such cases, where the parties are not legally advised, it is absolutely not uncommon for the parties to sign the agreement and then backdate it to the start of the commercial relationship believing that this will “catch” all the prior aspects of their relationship.
Legally speaking of course what they should do is put a provision in the contract which states that the terms of this contract shall also govern prior transactions which the parties shall henceforth treat as being regulated by those terms.
However, where lay persons write contracts themselves or download a from the internet, often these legal niceties are lost upon them.
In practice the courts are more sympathetic than one might anticipate.
The courts will generally try to construe contracts to give effect to the parties’ commercial intentions, not destroy them (see for example the decision of the Canadian Supreme Court in  2 SCR 6).
However, at common law this was a criminal offence (going by the contradictory sounding name of uttering a false document) and in most English law based legal systems it is still an offence today, although in many cases statutory provisions have superseded the common law (for example, in the British Virgin Islands see section 242 of the Criminal Code 1997).
However, in each case this could only operate where the contact is a “simple” contract rather than formally executed as a deed (ie signed, sealed and delivered).