Formal:
* C'est votre faute: This is the most literal translation and means "It's your fault."
* La faute vous en revient: This means "The fault lies with you."
Informal:
* C'est de ta faute: This is a more casual way of saying "It's your fault."
* C'est à cause de toi: This means "It's because of you."
Other options:
* Vous êtes responsable: This means "You are responsible."
* C'est de votre responsabilité: This means "It's your responsibility."
The best option depends on the situation and your relationship with the person you are speaking to.