GST applicable in state Govt. Subsidy

Are You received subsidy from govt to Your account directly...?!

As per Section 15(2)(e) of CGST Act 2017, the value of supply shall include subsidies directly linked to the price excluding subsidies provided by the Central Government and State Governments.
Here in this case, the subsidy is not to be included in the transaction value even if related to the price, as the subsidy of Rs. 20000 is by State Government.
So GST would be charged on Rs. 30000.

As per query.,

Subsidy not claiming by Seller. It's to buyer of the product. So, seller can be charge GST on his supply value...

Government do supply to end customer directly , means supply thrrough some mediatator or supplier . (Ie Gas Agencies)
Hence As per Section 15 of CGST act the GST is applicable on transaction Value ie 30k

Can issue bill in following manner: .

Material . 50K
Less : Subsidy. 20K

Net Value. 30k
GST . @ 5%. 1.5k

Total. 31.5K