It is often wrongly thought that merely by writing something which is false or, for example, writing someone’s signature on a document, that you commit the offence of forgery. This mistake is made sometimes by the prosecuting authority including the police.
In order to commit an offence, a defendant must create a false instrument which lies about itself, not which contains a lie. However, the mere creation of the document does not cause a person to be guilty, unless the prosecution can prove that it was used with intent to cause someone to accept it as genuine, with the intent to lose or gain something as a result.
It is not forgery to lie, even if that lie is in a document