You can rectify in Next GSTR1, if you are filling Monthly Return then you can rectify in Nov GSTR 1, in Quarterly Return You Can ammend it GSTR 1 of Dec
In Next Month Return either if sep pending, you can ammend it in Sep GSTR or upcoming GSTR, just check ammend option in GSTR 1, use option Ammended B2B invoices, entered invoice details and submit correction