On 1 April 1999, with the law on the introduction of the Ecological Tax Reform of 24 March 1999, the first stage of the Ecological Tax Reform came into force. This increased petroleum tax rates on motor and heating fuels and implemented the electricity tax. The law on continuation of the Environmental Tax Reform of 16 December 1999 made provision for increases in four further steps of the petroleum tax rates on fuels and ofthe electricity tax rate on 1 January 2000 to 2003 respectively. In addition, on 1 January 2000 the then varying petroleum tax rates on heavy fuel oil for heat and power production were amalgamated into a single petroleum tax rate. Besides this, on 1 November 2001 spreading of the petroleum tax rates for petrol and diesel depending on the sulphur content was introduced. The difference of 1.53 cents per litre compared to sulphurised fuel was initially applicable to low-sulphur fuel with a sulphur content up to 50 mg/kg and from 1 January 2003 to sulphur-free fuel with a sulphur content up to 10 mg/kg. The fifth environmental tax bracket was modified on 1 January 2003 by the coming into force of the law on progressive development of the Environmental Tax Reform of 23 December 2002. Among other things the petroleum tax rates on natural gas and liquid petroleum and on heavy fuel oil were increased.