Transitional input tax credit rules govern refunds, credit issuance and treatment of pending proceedings after the appointed day. Transitional provisions treat returns, refunds, credits and pending proceedings under the existing law: returned goods sold within six months prior to the appointed day and returned by unregistered persons within six months are eligible for refund of tax paid under the existing law, while returns by registered persons are deemed supplies. Price revisions under pre appointed contracts permit supplementary invoices, debit notes or credit notes within thirty days, with credit note tax reduction available only if the recipient reduces input tax credit. Proceedings and claims initiated under the existing law are to be disposed of under that law, with refundable amounts paid in cash and rejected or recovered amounts not admissible as input tax credit under this Act.