gst on final product if one raw material is exempt.

Simmer Khanuja (6 Points)

30 June 2017  
suppose we manufacture product A
1) Raw material A ₹100 ( applicable GST rate 18%) .. consumption percent 20%

2) raw material B. ₹100 ( tax free )
consumption percent 80%.

Now we sell that product(i.e. product A ) for ₹500 and applicable GST rate 28%.

so my question is whether we have to pay GST @ 28% on whole amount of₹500 or what??