What is a Billable user? under Manage Users in QBO
A billable user is a counted user from the number of allowable users (3) you can add in QuickBooks Online. It could be a regular or custom user and/or company Admin user. You will not be billed with this since it’s a feature that comes along with your subscription. You can see your Manage Users window by clicking the Gear icon in the upper right corner and choosing Manage Users.