What is the ruling on dealing with banks, and what should one do if they cannot avoid dealing with them?

Dealing with usurious banks is forbidden by Islamic law, and it is among the gravest sins. It is not permissible except in cases of extreme necessity, such as when one fears for their money from perishing or theft and finds no safe place other than the bank, or when transferring from one party to another and there is no way but through a usurious bank, or being forced to spend on oneself or one's dependents and finding no alternative but the bank. The permissibility ceases when the necessity is removed. Allah Almighty said: (But whoever is forced [by necessity], neither desiring [it] nor transgressing [its limit], there is no sin upon him. Indeed, Allah is Forgiving and Merciful).