Officials have no idea if most of the 200 tax breaks available to companies and private individuals in the Netherlands have any effect or what they actually cost the treasury, the national audit office says in a new report.

The current tax system, which dates back to 2001, has become paralysed by all manner of tax exemptions, discounts and other measures introduced by politicians since then, the audit office said.

Officials counted a total of 213 different rulings but said the financial impact of just 113 has been calculated. In six in 10 cases ‘it is unclear if they work and if they do, what the cost is,’ the audit office said.

The measures are as diverse as the 30% tax break on earnings for some expats, the tax discount for the self-employed and 6% value added tax rate. The impact of child, housing and healthcare benefits are not included in the report.

Tax minister Eric Wiebes said in a reaction that he had been trying to simplify the system. Assessing the impact of each ruling is expensive and the cabinet had decided to focus on evaluating the measures most relevant to policy and the budget, he said.