The law provides that expenses incurred by the recipient in relation to supplies made by supplier of goods / services is to be included in the transaction value, only where such expenses were to be borne by the supplier. However, in the instant case, it cannot be said that the suppliers are liable to incur the cost of booking of flight tickets or that the cost was incurred by the recipient on behalf of the supplier. Hence, the value of flight tickets booked are not required to be included by the Chartered Accountants in their invoice, for computation of transaction value of audit service.
(ICAI FAQ PUBLICATION 06-09-2017 VALUE OF TAXABLE SUPPLY: FAQ NO. 51)