As per Clause G of Rule 2(1)(i) of Service tax Rules, in relation to taxable services provided or agreed to be provided by any person located in non taxable territory and received by person in taxable territory, the recipient of service shall be liable to pay service tax.
Hence in respect of commission on exports payable to person located outside India, service tax liability shall fall upon exporter.
However vide notification 42/2012 dated 29-06-2012, specific exemption has been provided to exporters subject to certain conditons