This topic applies to Office 365 Enterprise, Office 365 Business Essentials or Office 365 Business Premium.
User passwords expire on a regular basis in Office 365. Global and delegated admins can make the user’s password expire after a certain number of days or set the password to never expire. Admins can also change the number of days before users are notified of password expiration.
- Sign in to Office 365 with your work or school account.
- Go to the Office 365 admin center.
- Go to Service settings > Passwords.
- If you don’t want users to have to change passwords, select Passwords never expire. If you select this option, users won’t get any reminders anymore to change their passwords.
- If you want user passwords to expire, type the number of days before the password should expire. Choose a number of days from 14 to 730.
- Type the number of days before users are notified that their password will expire, and then click Save. Choose a number of days from 1 to 30.
See Microsoft Office 365 Support page