I'm here to show you how to add your clients under your payroll subscription. We'll have to ad first the client's EIN to your subscription. These are the steps to follow:
Go to Employees > Payroll > Use My Existing Payroll Service.
Under Identify Subscription, choose Use Subscription Number xxxxxxx (Payroll Subscription Version). You can select Other: I have an existing subscription and a Zip Code. Then, enter your information.
Click Open, then select Next.
Select Next to add the company EIN. Select Print or Return to QuickBooks Desktop.
Once done, let's verify the Service Key. Go to the Employees > My Payroll Service > Manage Service Keys. Make sure that you can see the Active status when clicking View.
I've added these articles if you need a reference:
How do I get a listing of clients that are already under my enhanced payroll subscription? I cannot find a list so I can even figure out if I am close to 50?