RCM payable in freight charges missing

This discussion addresses how to handle Reverse Charge Mechanism (RCM) freight charges that were not declared in the GSTR-3B for FY 2018-19. The advice provided suggests that if the RCM liability was paid and its Input Tax Credit (ITC) availed in the subsequent year (FY 2019-20), it should be reported in the GSTR-9 for that year, not the 2018-19 return. Interest at 18% is applicable if the liability was booked in an earlier month but not declared.