Check what the next item for the taxpayer type field was and set the same value for the category type field.
This way it will jump to the item in the currencies tab.
Thanks for your reply
The thing is that po_currency_code (currencies block) is the next field only when the taxpayer type didn't refresh its text like shown above.
I already tried creating a trigger using this argue, but it stops at Category aswell :\
Thanks once again =)
Navigate to Help --> Diagnostics --> Custom Code --> Show Custom Events (select this option) and check which event is being triggered after you press tab in the Category field.