In GST we can use separate series of Invoice for SGCT(within state) & I GST (out of state)?
Yes you can and in my opinion you must
Yes there is no mandatory format as yet
No, You Cannot Invoice Series must be Maintain in Regularly formate
According to Rule 1 (b) of the Rules on Tax Invoice the tax invoice can be issued in multiple series. The most important point is that the serial no. must have the year in question. For example 17/18 for the current financial year.