The three-month cap (§ 551 BGB)
A German residential deposit may not exceed three months' net cold rent. Anything above that is invalid to that extent — you can reclaim the excess, even during the tenancy. You are also entitled to pay in three equal monthly instalments, and the landlord must keep the deposit in a separate, interest-bearing account.
How long may the landlord hold it?
There is no fixed statutory deadline; courts grant landlords a reasonable examination period, typically three to six months after handover. Only a pending utilities settlement justifies withholding a proportionate part for longer. Months of silence are not something you must accept.
Which deductions are legitimate?
Only concrete, provable claims: unpaid rent, outstanding utility balances, or damage beyond normal wear and tear. Worn carpets, faded walls, and ordinary traces of living are not damage. The handover protocol is often the decisive piece of evidence — for both sides.
Demand repayment in writing — with a deadline
The most effective first step is a written repayment demand with a concrete deadline (two weeks is customary) and your bank details. Mietsicht drafts it from your contract, tracks the deadline, and shows the escalation path if nothing happens — up to tenants' associations or formal collection proceedings.