Institution Postdating Cash Credit

I am formulating a complaint to a federal financial regulatory agency and I want to ensure my complaint is very clear, especially in terms of how a credit to an account must be dated, whether legally or in terms of mandated accounting standards (e.g., GAAP or IFRS).

However, I first want to be reasonably sure there are no legitimate reasons whereby an institution may change the date of a cash deposit where the credited funds are immediately available for withdrawal (i.e., no holds). Any comments would be appreciated.