@Beth1107 

QB should make this process much easier.  QB should give you the option to choose the date with which the void is effective, but it doesn't.  If you just click 'Void' on the check, QB voids the check as of the original check date.  So, at this point, to void the closed-period check in the current period, make a deposit dated in the current period for the amount of the check and assign the same account to the deposit that was assigned to the check.  The next time you reconcile, clear the check against the deposit and you're all set.