To find out the password expiration date for an Active Directory user you must first determine your domain’s password expiration policy and then when the password was last set.
Find your Domain Password Expiration Policy
import-module activedirectory Get-ADDefaultDomainPasswordPolicy
Property MaxPasswordAge will tell you the default password expiration policy
Determine Date User Password Was Last Set
import-module activedirectory Get-ADUser <username> -properties passwordlastset, passwordneverexpires
The user’s password will expire the date the password was last set + the value of MaxPasswordAge