Inter-State supply reporting: ensure place-of-supply-wise disclosure in returns and correct reversal of ineligible input tax credit. Registered persons must report place-of-supply-wise inter-State supplies to unregistered persons, composition taxpayers and UIN holders in Table 3.2 of FORM GSTR-3B and corresponding GSTR-1 tables; portal auto-populates Table 3.2 from GSTR-1 but suppliers remain responsible for accurate PoS. Table 4(A) of GSTR-3B is auto-populated from FORM GSTR-2B; permanent ineligible credits and mandatory reversals (including section 17(5) and rules 42/43) must be shown in Table 4(B)(1), temporary reversals in Table 4(B)(2) (reclaimable later in 4(A)(5) and shown in 4(D)(1)), and Net ITC in 4(C) equals 4A minus the sum of 4B(1) and 4B(2).