backdate
/ˈbækˌdeɪt/
verb
backdates;
backdated;
backdating
backdates;
backdated;
backdating
Britannica Dictionary definition of BACKDATE
[+ object]
1
:
to give (something) an earlier date than the actual date
:
antedate
2
:
to say that something began or became effective at a date earlier than the current date