Staff at the national tax service are going on strike next week in a dispute over pay.

Four trade unions announced the action, which will affect two departments at the Belastingdienst, on Monday. Unions are demanding a 3.5% pay rise, a figure the government says is too high.

Interior affairs minister Kajsa Ollongren has said she will make a counter-offer at the end of the month once it is clear how much money is available, but the unions say they are not prepared to wait.

Civil servants’ wages were frozen for four years from 2011 to 2015 at the height of the economic crisis. Since then they have increased by 1.25% in 2015, 3% in 2016 and 1.4% last year.

Negotiations broke down last December over pay packages for 118,000 civil servants. The FNV union has declined to sign off on previous deals because the pay rises were partly offset by cuts to pension contributions.

Marco Ouwehand, of the FNV, said the industrial action would continue until the government came up with a ‘serious’ pay offer. The union is also considering calling out workers for the workplace safety inspectorate SZW.