Allow me to share some details about sending your clients a backup copy of their company file.
The option to only send their payroll information is not available in QuickBooks Desktop (QBDT). The possible reason for this is your client company file doesn’t have a payroll service key. Thus, they’re unable to view their payroll information.
That being said, you’ll want to add your client to your payroll service. To add them, you'll need to provide them your payroll service key. If you don't have your service key, we can use the Automated Service Key/Disk Delivery Key Tool to get it. Once you have it, let your client enter it into their QBDT software.
Let them press CTRL+K on their keyboard to open the QuickBooks Service Keys window. From there, have them enter the service key and they’ll be able to view their payroll information.