Input tax credit on purchase under dvat

DEAR SIR,

I WANT TO KNOW THE TIME PERIOD WITHIN WHICH INPUT TAX CREDIT ON PURCHASE CAN BE AVAILED.

WE HAD PURCHASED GOODS OF RS.11,250( INCLUDING TAX RS.1250 ) ON 13/03/12 BUT WE COULDN'T TAKE THE BENEFIT OF TAX DUE TO CLERCKIAL MISTAKE & FILED THE RETURN ON 25/04/12 ( ON QTR.BASIS).

NOW WE WANT TO TAKE CREDIT OF TAX IN MAY'12. CAN IT POSSIBLE ? PLEASE SUGGEST ME