Circular No. 71/45/2018-GST dated 26th October 2018 
Advance tax period of Registration of Casual Taxable Person and refund of excess distribution of credit by ISD- Clarificatio by CBIC-Circular No. 71/45/2018-GST dated 26th October 2018:
It has been clarified that Casual Taxable person (CTP) is required to deposit estimated net tax liability not the gross tax liability while applying for Registration. Advance tax is required to be deposited taking in consideration estimated eligible ITC.
CTP cannot take registration for more than 180 days. In case period is more than 180 days normal registration will be required without deposit of advance tax and registration can be applied for cancellation once purpose of registration is over.
In case of credit distribution by ISD, some unit may get excess credit than such unit may deposit the excess amount voluntarily along with interest using Form GST DRC-03.
Refer: Circular No. 71/45/2018-GST dated 26th October 2018