A party has issued us bill for services rendered in the month of january 2009 or before that period. Bill has been issued on 13/02/2009 and he charged ST @ 12.24%. Now we are paying this bill in the month of march 09 and now the Service Tax rate is 10.3% after 24/02/2009. Kindly guide us should we pay ST @ 12.24% as charged by party and take Cenvat credit of same or we should pay ST @ 10.3% becuase the liabilitiy of ST payment arise after receiving payment for the services rendered.