Declaration Forms C obsolete; statutory C forms declared invalid, specific C declarations listed and rendered non operative. Declaration Forms 'C' are declared obsolete and invalid for all purposes with effect from the date of issuance or downloading of the Statutory ('C') Forms under sub rule 13 of rule 5 of the CST (Delhi) Rules, 2005. The notification lists affected C forms by reference number and records form type, issued party identifiers, party names and addresses, valid amounts and the tax periods for which those C declarations are invalidated.