Short Answer
Your landlord possesses the absolute legal right to demand a monthly surcharge if you introduce a subtenant into the property.
This extra fee, known as an Untermietzuschlag, is legally justified to offset the increased structural wear, tear, and resource consumption caused by an additional resident.
What Most Expats Don't Realize
You brought a roommate into your apartment after receiving a basic verbal agreement from your landlord, assuming your baseline warm rent would remain completely unchanged. You opened your mail a month later to discover a formal warning and a retroactive penalty fee because you had refused to sign an official lease amendment containing a fixed monthly surcharge. Because you treated subletting as a cost-free personal right, you were forced to pay €550 in cumulative retroactive fees and administrative costs to stabilize your contract.
What To Do
- Email a formal request for subletting approval to your landlord and ask them to specify the exact monthly surcharge amount in writing.
- Review the proposed lease amendment to ensure the added fee falls within the standard market rate of €30 to €50 per month.
- "Ich bin mit dem angemessenen Untermietzuschlag einverstanden." (I agree to the reasonable subletting surcharge.) — send this written confirmation to finalize the contract update legally.
The Truth
Germany’s civil framework permits property owners to monetize the expanded usage of their real estate assets when extra occupants move in. The system enforces these specific surcharges strictly, leaving tenants who refuse to sign the updated rate schedules exposed to immediate lease cancellations for unauthorized usage.