Reg. Needed or not

For audit of branches outside your state, you are not obliged to register in that state. You just need to raise invoice adding integrated GST instead of CGST and SGST.

ok.. you dint form your question properly. So your query is that you undertake an audit of Bank having branch in Punjab and total billing is less than 20L, and since it is an intra-state supply of service, you do not need registration. But in case you are doing audit of Branches outside Punjab (but audit is carried out within Punjab as I understand), whether you need to register or not.. I believe that since you are providing the services to HO as HO is required to carry out audit of its branches spread all over.. and hence the place of supply shall be the location of HO i.e. Punjab.. The location of branches would be irrelevant. Also, you shall be billing HO itself.. Hence, if your billing is less than limit of 20L, you do not need to register under GST. However, bank would be required to pay GST on your billings under RCM as per section 9(4) of CGST Act.