Taxpayers of taxes on natural gas and certain other gases who have become liable to declare and pay excise duty are obliged to submit a tax return and pay the tax by the twenty-fifth day after the end of the tax period in which the liability arose.

The obligation of the supplier, the taxpayer under Section 3(1)(e) (natural or legal person who consumed untaxed gas, except for tax-exempt gas) and the holder of a permit to acquire tax-exempt gas, the operator of the distribution system, the operator of the transmission system and the operator of an underground gas storage facility to keep records of the quantity of gas for tax purposes for individual tax periods.

The holder of a permit to acquire tax-exempt gas is obliged to notify the tax administrator of any change in the data within 15 days of the date of the change.

Solid fuel tax payers who have become liable to declare and pay solid fuel tax are obliged to submit a tax return and pay the tax by the twenty-fifth day after the end of the tax period in which the liability arose.

The obligation of the supplier, the taxpayer under Section 3(1)(c) (natural or legal person who consumed untaxed solid fuels, except for tax-exempt solid fuels) and the holder of a permit to acquire tax-exempt solid fuels to keep records of the quantities and types of solid fuels for tax purposes for individual tax periods.