Going sub contractor tax

My son has finished his apprenticeship in bricklaying and is working in the south of Ireland, living in Northern Ireland. He is to go sub contractor now ..I have a pps number . I do I go about registering him tax wise etc ..Tia

Hi Clairecunningham,
If he needs to complete a Self Assessment  tax return then he can register here:
Check how to register for Self Assessment.
Also if working as a subcontractor he can register here:
To register for the Construction Industry Scheme (CIS) you’ll need:
Thank you.