Isn't the address on the W-4 form supposed to be for receiving tax forms in the mail?

Hello, jvulcano2.

I'll share some information about the address field.

For now, we're unable to offer the option to have a P.O Box address in the W-4 page. Entering the information will give you an error "Address can't have a P.O. box". This is a default reminder that QuickBooks accepts only a physical address. 

You'll want to check the Ask this employee to enter their personal, tax (2020 W-4), and banking info with QuickBooks Workforce box. This will send an invite to your employee, so they can enter their W-4 information. Your employee might be able provide a physical address. 

Here's a sample screenshot of what the option looks like when adding an employee:

To learn more about adding an employee and running payroll in QuickBooks Online, you can read these articles: 

• Add a new employee to your payroll
• Process or run payroll

Please don't hesitate to ask additional questions about your payroll or if you need help with other task in QuickBooks Online. I'll be around to give the details and steps. Have a good day ahead.