accounting entry for grade loss

We can pass the entry say Supplier A/c Dr to Loss on grade fail A/c.

What will be the group for loss on grade fail ledger in tally?"

Further how should we bill the same to our buyer as we have to bear loss amounting rs 20 lakh.

Should i adjust the amount in bill itself by lowering the rate or send bill for the full amount and issue a credit note or ask the buyer to issue a debit note.

1. We need to account the bill for full amount in our books.
2. For the quality loss, pass an entry debiting the supplier to that extent i.e.Rs.30 lakhs by crediting to "Loss on Quality a/c"
3. To this extent, supplier will need rise a Credit note on you. ( Else, you may rise a debit note on supplier.  Effect will be the same.)