Concessional GST rate for petroleum operations limits state tax on listed supplies subject to prescribed certificates and compliance Intra State supplies of goods listed in the annex for use in petroleum and coal bed methane operations are exempted from that portion of State GST above a concessional rate, subject to prescribed documentary conditions: a certificate from the Directorate General of Hydrocarbons confirming requirement for the operations (naming subcontractors where relevant), affidavits and undertakings by subcontractors and contractors, transfer approvals with undertakings and foreign exchange certification where applicable, and a mechanism to pay tax on depreciated value upon disposal.