Input tax credit transition: registered persons may transfer carried forward VAT credits into electronic ledger subject to conditions. Registered persons not opting for composition may transfer pre existing value added tax credit into their electronic credit ledger if admissible under this Act and after satisfying return filing and prescribed documentation requirements; excluded are credits not admissible under this Act, credits lacking required prior returns for the six months before the appointed day, and certain unsubstantiated central sales tax claims which remain refundable when substantiated under prior rules. Specific transitional rules govern unavailed capital goods credit, inputs held in stock, mixed suppliers, fixed rate taxpayers, and credits for inputs received on or after the appointed day subject to time and documentation conditions.