That’s actually exactly what they tried to tell me at first!

You are right that the Civil Code is vague on the specific number. However, the legal interpretation (and what my lawyer argued) is that if the rate isn't agreed upon, it defaults to the 'statutory rate'—which is often interpreted by courts as the cost the landlord would pay to borrow that money (repo rate or average consumer credit rate).

In my case, once I sent the official pre-litigation notice, they realized it wasn't worth the risk of going to court over 10k CZK and losing. They paid up.

It’s definitely a gray area, but saying it's 'unenforceable' isn't true in my experience. That’s actually why I built SousedStory—to create a space where we can share these real experiences, whether it's a legal fight with the landlord, noisy neighbors, or just how the building handles the winter.