If you hire an external person, set up this person as a subcontractor worker.
This setup is required for a subcontractor worker:
The Worker type is Contractor.
On the Worker form, on the Employment page, in the Contractor details section, define a Vendor that is marked as Subcontractor.
For more information on hiring a new worker, refer to Key tasks: Workers.
Steps
Go to Human resources > Workers > Contractors.
Click Edit.
In the list, click the link in the selected row.
Click the Contract employment tab.
Expand the Contractor details section.
In the Vendor field, enter or select a value.
Notes
You can review, for each subcontractor, the list of subcontractor workers here: Project management and accounting -> Setup -> Advanced project management -> Subcontract -> Subcontractor workers. All Contractor workers that are linked to Subcontractor vendors are automatically listed here.