It is possible for a consumer to deposit a post-dated check early. Whether or not this is an option usually depends on a specific bank's policy. Some banks hold the check until the date written on it, and others deposit it immediately.
Post-dated checks can also get deposited early if the deposit is made at an ATM rather than with a bank teller, as the date may not be noticed. If a post-dated check is deposited early, the check writer may have overdraft fees if there is not enough money in his account to cover it. The recipient may also impose fees if the check is returned for insufficient funds.