Doctrine by topic · DGT Observatory
How the DGT's position on this topic has evolved, and the rulings it rests on.
Current position
The exemption from the Hydrocarbons Tax for cogeneration applies to the production of electricity in authorized power plants or combined cycle plants. Gas intended exclusively for the production of heat or steam in recovery boilers does not benefit from said exemption. Regarding biogas, its use as fuel in cogeneration engines is subject to the tax, unless the requirements for exemption due to electricity production are met. Accrual is determined at the moment when the price is due in the billing.
The DGT's position has moved from treating the use of biogas in cogeneration as a use as fuel subject to the tax (V2662-15), to qualifying the application of the exemption for electricity production. It has been specified that the exemption requires authorization according to the Electricity Sector Law (V1770-19) and that it does not extend to gas intended solely to generate steam or heat (V3063-19).
Turning points
Establishes that the exemption only applies to authorized power plants or combined cycle plants, excluding mobile generator sets.
Determines that gas injected into recovery boilers to generate only steam or heat is not entitled to the exemption.
Analysis based on 13 of 13 rulings with a stated position. Updated 27 September 2026.