What is the ruling of Islamic law regarding renting out a shop for one million dinars and writing the contract for two hundred and fifty thousand dinars to evade taxes; is it permissible because taxes are forbidden in Islam, or is it forbidden because it is a deception of the state?

If the tax is unjustly levied, then there is no sin in evading it, defrauding it, or assisting those who do so. However, if the state imposes it in exchange for services or to meet the needs of the nation and the interests of the people, then it is not permissible to defraud it. Concealing the amount of rent is considered falsification and fraud.