Categories

Hoping someone can help me. We are looking at introducing categories into the business to divionalise the sales/purchases/employees so they sit under their "category". Basically trying to report on how each "division is tracking" financially.

I can see where you can allocate the category to a sale, purchase, Spend money etc however can't see where you can catergorise wages through their employee card? Is this possible? 

Any help would be appreciated.