All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Taxes are of two types: permissible taxes and impermissible taxes. The permissible taxes refer to the taxes the government imposes on the citizens in order to supply necessary facilities, such as paving roads and building hospitals and schools with the taxes collected. On the other hand, the impermissible taxes are the taxes imposed by the government on the citizens without providing any services in return or those imposed on them while the treasury has enough money which suffices to provide the necessary facilities and public interests. This type of taxes is prohibited by the Sharee‘ah. For further information see Fatwa 89947.
Thus, if the taxes imposed on you belong to the second type, it is permissible for you to evade their payment. Also, if the tax levied on you is overestimated as you mentioned, there is no blame to evade paying the extra amount. In this case, it is permissible for you to give bribe to protect your money. The prohibited bribe is the one that a person pays in order to get what is not his lawful right. But, the bribe that one pays to get his right or alleviate harm or injustice from him is permissible according to the majority of scholars. The sin of such a bribe is borne by the person who receives it not the one who offers it.
As for paying the taxes or bills, even if they are unfair, or paying the bribe from the bank interests, then this is not permissible. That is because the person who does so has protected his money with these interests, yet he supported himself with them. However, it is obligatory on the Muslim to get rid of Riba interests by spending them in the public interests of Muslims, such as paving the roads, building bridges, schools and orphanages, or giving them away to the poor and needy people. Therefore, it is permissible for you to give these interests to your sister-in-law if she is poor, since she is included in one of the channels through which Riba interests may be spent. For further information see Fatwa 83894.
Finally, we alert you that it is not permissible for the Muslim to deposit his money with Riba-based banks because this involves consuming Riba and cooperating with the bank on sin and aggression even if the interests would be disposed of. However, if the Muslim failed to find an Islamic bank where he can keep his money, he would be allowed to open a current account or the like in a Riba-based bank due to the need that must be weighed according to its proper value. For further information see Fatwa 83783 and 84864.
Allaah Knows best.