The Section 65(19) of the Finance Act, 1994 has given very wide definition of the term "Busi Aux Service" (BAS). As per the clear reading of the definition, the Commission paid to the Directors does not attract Service-tax.
The Commission paid to Directors is in the nature of incentive to boose the sales of the Company. It is not the Commission per se. The purpose of such commission is to link their performance with company's result. Secondly, the Directors are not Commission Agent and hence incentives (or commission) paid to them would not attaract Service-tax.
Of late, Exise Dept started asking queires in this direction but is not standing on strong legal footings. In order to avoid this, many Companies use the word "Incentives" instead of "Commission".