Could is used with any subject to ask for permission. For example “Could I open the window?” or “Could you open the window?” are both grammatical. Be careful with may. When making a request using may, only I can be the subject.

How do you politely ask for permission?

“May I…?” is the most common English polite expression used to ask for permission. Though this expression is used in formal contexts, you can also use informal and semi-formal situations. The expression “May I…?” polite by nature, but if you put a “please” at the end, it will sound politer.

Could is permission or request?

The modal verbs (or modals for short) of permission are can, could and may. These verbs are used to politely ask for permission, to make a request, and to offer help to someone.