GST return filing: companies may use GSTR-3B and GSTR-1 or invoice facility during a limited transitional period. The amendment to Rule 26(1) permits a registered person registered under the Companies Act to, for the period 27th April, 2021 to 31st May, 2021, furnish the return under section 39 in FORM GSTR-3B and the details of outward supplies under section 37 in FORM GSTR-1 or using the invoice furnishing facility, with such filings verified through electronic verification code (EVC).