Service tax return filing- st3 - jul to sep2012

Dear All,

I hope the due date for filing ST3 for July - Sep2012 is 30th April 2013. Can i file s.tax return for a company without interest component. The client has not paid the tax amt within the due date. Should i wait until he provides me with the details of interest payment challan or can i proceed further in filing the returns without interest amt????