Ever since the discovery of the natural gas field at Slochteren, Groningen, the state-owned monopoly Gasunie has administered the supply of gas. Even on a European level, Gasunie was a major player covering some 20% of European demand. For a long time the upcoming liberalization met with fierce opposition, but eventually the company, the Dutch government and oil companies Shell and Exxon decided to divide the company into two separate entities. Liberalization should guarantee improved quality, service and relatively lower costs for the customer. This means that, in order to keep their customers, suppliers will have to make an extra effort.

Since 1 January 2002, all large-scale consumers have been free to choose their own gas supplier. Energy regulator DTe feels the bargaining position of these large-scale consumers is sufficiently strong, which is why DTe no longer regulates tariffs in this market segment. They regard a change of supplier as a rational and professional purchase process. A customer becomes a large-scale consumer when his consumption surpasses 170,000 m³.

Since 1 July 2004, small consumers are also free to choose a supplier. Every customer consuming less than 170,000 m³ falls under the 'small consumer' category. Energy regulator DTe sees to it that energy suppliers respect the rules, thereby protecting the consumer. Small consumers are often very hesitant when it comes to switching suppliers.

By 1 July 2004, the Dutch gas market was fully liberalized.