Six Dutch sea ports should pay corporate tax over their income in order to meet EU rules on state aid, the European Commission said on Thursday.

The port authorities in Rotterdam, Amsterdam, Zeeland, Den Helder, Groningen and Moerdijk had been exempt from paying corporate taxes on their income.

‘Cross-border competition plays an important role in the ports sector and the commission is committed to ensuring a level playing field in this important economic sector,’ the EU’s ruling body said in a statement.

‘The commission’s decisions today … make clear that if port operators generate profits from economic activities these should be taxed under the normal national tax laws to avoid distortions of competition,’ competition commissioner Margrethe Vestager said.

Two months

The Netherlands was told by the commission in 2013 to end the corporate tax exemption for public companies and did so for all but the six ports last year.

The commission has now given the Netherlands two months to take the necessary steps to remove the exemption to make sure that from 1 January 2017 the six ports are subject to the same corporate taxation rules.

France and Belgium have also been told to align their port taxation systems with state aid rules.