Service tax on m.p & security by service receiver

BUT SIR, HE IS ASKING WHETHER HE IS LIABLE TO PAY SERVICE TAX ON BILL OF MARCH 15 RAISED IN APRIL 15 TO A CORPORATE ENTITY. SO IF I AM CORPORATE ENTITY AND I RECEIVED A BILL OF MARCH15 IN APRIL 15 SO WHETHER I HAVE TO PAY 100% OR 75%. BECAUSE AS PER THE ACCRUAL SYSTEM THE SERVICE PROVIDER HAS TO BOOK ITS BILL IN MARCH 15 SO HE IS FALLING TO PAY 25% AND ME 75%. SO THERE IS DOUBT IF BILL RAISED IN APRIL 15 FOR SERVICE PROVIDED FOR THE MONTH MARCH 15 WHAT WILL BE LIABLITY OF CORPORATE ENTITY AND SERVICE PROVIDER