Is there a cost in activating the "payroll" option in Quickbooks?

Hi erik9,

If you have purchased any subscription of Quickbooks Online, then the payroll is automatically included in your subscription free of charge. 

Depending on which subscription you selected will depend on how many free employees are included in your payroll (Simple Start - 4, Essentials - 7, Plus - 10)

To use the payroll features, just go to the Employees tab, and start payroll from there.

Hope this answers your question!

Kristian.