Due date for payment of service tax

REceipt of refundable deposit may not amount to receipt of consideration. Hence date of bill is the point of taxation.

quiry; regn.allready done in last year but as billed just for 3.50 lacs no ST COLECTED & deposited in last year.In current year billed for 3.00 lacs without charging ST and I have to raise two bills for 4.00lac each. Should Icharge ST ON BOTH bills & if so what about st not collected on first 3.00 lacs.AmI require to bear the same or will it be covered under 10.00 lacs exemptoin.

please provide me a due date of service tax of company case and due date of  service tax return