Four opposition parties have agreed to talk to the government about support for its tax reform plan, broadcaster Nos says on Thursday.

Three parties which have previously supported ministers in the senate – D66, ChristenUnie and the SGP – have been joined by GroenLinks at the negotiating table, the broadcaster says.

The Christian Democrats, who had been expected to join in, have opted to stay out of the discussions.

Ministers need opposition party backing to ensure their reforms get majority support in the upper house of parliament. The six-party alliance controls 40 of the 75 seats in parliament.

The four parties have, however, said they will not start the discussions until the cabinet has sent a briefing to parliament and the issue has been debated in the lower house.

Three stages

In total, the government plans to cut taxes and premiums by €5bn, with or without the agreement of opposition parties. This will be done by making changes to the tax free allowances and reducing the middle income tax band from 42% to 40%. The 52% tax rate will not kick in until €65,000, compared with €57,500 at present.

The second stage of the reforms, which will require agreement from coalition parties to ensure it passes through the upper house of parliament, involves increasing the 6% value-added tax (btw) rate to the higher rate of 21% on some products and services. Small firms and retailers have already condemned this proposal.

The third stage, which still has to be worked out in detail, will involve giving local authorities more tax raising powers in return for further cuts in national taxes.