GTA is not always covered in RCM. it is only when it provide service to person who are covered in RCM. i.e body corporate, reg firm, reg person in GST, reg society. If a GTA provide services to the person who are not covered in above list than GTA have to pay GST. Further it is rumor in the market that GTA is not required to get reg in GST. Please note that if a GTA provide services only to person covered in RCM than GTA is not required to get registered in GST. but if even 1 % of its turnover involve services to other person he is liable to get registered under GST if its aggregate turnover is more than 20 lakh.
“aggregate turnover” means the aggregate value of all taxable supplies [excluding the value of inward supplies on which tax is payable by a person on reverse charge basis], exempt supplies, exports of goods or services or both and inter-State supplies of persons having the same Permanent Account Number, to be computed on all India basis but excludes central tax, State tax, Union territory tax, integrated tax and cess.