Praise be to Allaah.
The following question was put to Shaykh Muhammad ibn Saalih al-‘Uthaymeen, may Allaah preserve him, who replied as follows:
It seems that it is not permissible, because he has a contract with them, and if he has a contract with them it is not permissible for him to try to cheat their system.
Question: even if it involves an unfair tax?
Answer: but he agreed to that from the outset.
And Allaah knows best.