Who has to register
The FTA registration service page lists juridical persons subject to corporate tax under FTA Decision No. 3 of 2024, plus natural persons whose business turnover in the UAE exceeds AED 1 million in a calendar year. A UAE branch of a domestic company does not register separately, because the FTA treats it as part of the head office. The FTA can also require certain exempt persons to register.
A VAT registration does not cover this. The FTA corporate tax FAQs state that taxpayers must register for corporate tax even if they are already registered for VAT.