Adding a field to a ticket

Good Day

I am looking for a way to add a field to every ticket so that you can place the ticket against a location. For example, assigned a ticket to a tech and specify what branch it is i.e L.A , NYC ext

The reason for this is that we are going to start charging for our labor. In order for our accounts department to bill the correct cost center based on my spice report. I need to have a way to include that in the ticket and thus the report.

Thanks