After I got that actually password doesn't disappear after expiry date, and still there(as mentioned here: Does the password truly expire?)
I would like to know if and how can the system/domain admins - get answer on input string - if that is the old password or not.
(if it is - give to the user permission to select a new password. if not - deny.)
The idea behind the motivation is I want to make my own application for changing password instead the windows default.