2 business under same pan

What  is aggregate  Turnover  of  another business which is unregistered ? .  

Turnover for both business is below 20 lakhs (PAN based)

What  is Business ?. Is it Voluntary  registration ? , because you have mentioned Turnover is  bellow 20 lac .  please  elaborate  in detail . 

If you are registered then you are liable for tax for all business under same pan. Provided other business is not an exempt supply

Yes. voluntary registration is taken & the business is provoding amc sercices of water filter

It's not an exempt so you need to pay GST on same supply.. if you don't want to pay GST on this business then you can constitute a firm and carry business under that pan

Gst is liable to be paid in the following cases:
1.depending on the turnover.
2. depending on the transactions.
3. taxable person engaged in merchandising of goods and services .
4. if threshold limit is crossed then you hv to pay gst.
Every taxable person is liable to pay CGST SGST EXCEPT WHERE TAX IS PAYABLE UNDER REVERSE CHARGE.