I cannot speak directly to federal or state legislation in the USA, but it is a
generally accepted principle of law in common law countries that it is the
moment of taking actual possession of the gift that determines the tax year in
which a tax deduction occurs. Indeed, one of the things auditors look for, in
auditing financial transactions of registered charities is any back-dating of
deductions.

I would be MOST surprised if the tax law situation were much different in the
US of A.

Harry Needham
(inactive) Certified Fraud Examiner
Canadian War Museum