how to declare debit note/credit note in gstr9?

Debit note issued regarding purchase return, where will be effect of debit note in GST 9 ??

If the debit note regarding purchase return includes GST, then the ITC Claimed in GSTR-3B would be net of debit notes, and there is no separate disclosure required for purchase related debit note in GSTR-9. Table 6A of GSTR-9 is net of debit notes only. Hence no requirement of separate disclosure.

No table 6A is not net off of Debit/Credit notes..so i am facing the issue...what to do? Where to report the reversal of ITC on account of credit note issued to us by the supplier?

In 3B we have shown it in Table 4(B)