Amendment under section 50 adjusts prescribed figure in a listed notification entry, with retrospective effect applying from notified date. An amendment under sub-section (3) of section 50 of the Goa Goods and Services Tax Act, 2017 substitutes the figures '24' by '18' in the Table against serial number 2, column (3) of the cited notification; the amendment is deemed to have come into force from the first day of July of the relevant year.