Also called GST debit note, purchase return note
Under GST, a debit note is issued by the supplier when the original invoice charged too little, for example when the price was revised upward or the quantity was more than billed. It increases the taxable value and the tax on that invoice.
In everyday trade, buyers also use the term for their own note when they return goods to a supplier or report a shortage. That note tells the supplier how much to reduce the bill. The supplier then normally issues a GST credit note for the same amount.
A distributor bills a shop ₹15,000 plus 5% GST, but the agreed price was ₹16,000. The distributor issues a debit note for ₹1,000 plus ₹50 GST. If instead the shop sends back 10 damaged cartons worth ₹1,200, the shop raises a purchase return note and waits for the supplier's credit note.