Furnished and Short-Term Letting: Three Regulators, One Headache

Furnished and short-term letting looks like free yield. It is really three separate regulatory layers stacked on one flat.

1. Zweckentfremdung (public law). Under the NRW Wohnraumstärkungsgesetz (WohnStG NRW), municipalities may adopt a Zweckentfremdungssatzung, and Bonn has one. A permit is needed to let to changing short-term guests beyond the allowance, to leave a flat empty more than six months, to use more than half the floor area commercially, or to demolish or render a flat uninhabitable. Bonn's permit-free allowance is reported as up to three months / max 90 days per calendar year (students up to 180 days with proof), and lettings must be registered for a Wohnraum-Identitätsnummer to be quoted in listings. These numbers are municipal and change – confirm with the Stadt Bonn before you list anything.

2. Rent law. The Mietpreisbremse applies to furnished flats too. The cap is measured against the ortsübliche Vergleichsmiete of the unfurnished flat, and the Möblierungszuschlag on top has no statutory formula. Courts improvise – Berlin practice writes furniture off over about 10 years at roughly 2% of current value per month, Hamburg over 7 years. Show the surcharge separately in the contract and keep an inventory with values; an unjustifiable surcharge is simply overpaid rent the tenant can reclaim under §556g.

3. The exemption you probably do not have. §549(2) Nr. 1 BGB disapplies most tenant protection for housing let "zum vorübergehenden Gebrauch" (temporary use). This turns on the actual purpose, not the label or the contract length. If your tenant makes the flat their centre of life, it is an ordinary protected tenancy – retroactively, at a capped rent, with full notice protection. Nor can you simply write a fixed-term contract: §575 BGB allows one only for three stated reasons (own use, planned demolition/major works, letting to an employee), declared in writing at the outset.

Coming: the "Mietrecht II" bill (cabinet 29 April 2026, first Bundestag reading 10 July 2026, not yet law) reportedly caps the Möblierungszuschlag near 10% of net rent and defines short-term letting as roughly six months, extendable to eight.

For a first flat under €200K, plain unfurnished long-term letting is the far lower-variance choice.