Depends on where you live. In Germany the Landlord MUST charge the minimum price per square meter and pay tax accordingly. They don't care which currency you're paid in for as long as you pay the tax in EUR.

It's a ridiculous law. Let's assume you have a friend who's in a tight spot, lost his job, his home and you have an empty property. You may not let it to your friends for free for a couple of months. It's against the law. Not your property!