CNG blended with biogas exempted from excise to the extent of tax on the biogas, subject to recordkeeping and quarterly reconciliation. The notification exempts Compressed Natural Gas (CNG) blended with Biogas or Compressed Biogas (CBG) from excise duty to the extent of tax paid on the Biogas/CBG contained in the blended fuel, subject to manufacturer compliance: maintain detailed blending records at registered premises, submit quarterly reconciliation statements certified by the statutory auditor to the jurisdictional Commissioner by the 10th of the month following each quarter, and pay any short-paid duty with applicable interest after reconciliation.