ことになっている

A plain, non-past verb + ことになっている is used to mean that "something has been decided and the result of that decision is still in effect." In my head I sometimes read it as "It has become that..." because that kinda sounds like a formal way of announcing a new rule or decision that's in place. This grammar point is commonly used in such scenarios, along with stating one's schedule.

授業を休む時は先生に連絡しなくてはいけないことになっているが、忘れてしまった。
It's a rule that if we miss class, we have to contact the teacher, but I forgot.

子どもがこのレストランに入ってはいけないことになっているんだよ。
It's been decided that kids cannot enter this restaurant.

私の家では食事の後、自分が使ったお皿を洗うことになっている。
At home after we eat now, we're supposed to wash the dishes we used ourselves.

その美術館の中時に、写真を取ってはいけないことになっているよ。
It's been decided that you're not supposed to take pictures when you're in the museum.