What is the ruling on working 40 hours a week under a 10-hour contract to pay less taxes, knowing the difficulty of finding halal work in the Netherlands?

If the employer states a number of working hours in the contract that is contrary to reality, as a way of evading unjust taxes that are taken unlawfully and spent improperly, then there is no objection to using artifice to nullify or reduce them. However, if the taxes are legitimate, it is not permissible to use artifice against them. If you are compelled to remain in this job due to necessity or dire need, then it is permissible for you to do so until you find another job that does not involve this violation.