Liability of Service Tax on Freight "

Dear Friends,

My query is regarding Outward Freight [Carriage Outward] paid on behalf of Customer..see the points below..

1.We are making the freight payments on behalf of our customers and later on charging the same to the customers in access of Invoice Value

2.Our Transporters/Courier companies are raising the bills on monthly basis to us on which they are charging the Service Tax as applicable %

Pls.clarify whether still such expenses are liable for Service Tax ?

Sometimes it happens that we might get the 100% of the freight paid on behalf of customers and also possible of not getting the full amount paid...