Straight to it, because this is what tenants ask me most at move-out: the landlord may only keep from your deposit what you genuinely caused. If a key is missing, they can demand a replacement or, in a serious case, a cylinder swap. A whole new system "for safety" at your expense, just because you are leaving, is not on. Full stop.
I run the night and weekend emergency service in Frankfurt, and I see these move-out fights constantly. Honestly. Most landlords do not scam, but the few who do pocket hundreds of euros for locks that nobody needs to change. Once you have understood where the line runs, you stop letting it happen to you.
What a landlord may actually deduct from the deposit
The deposit is your money. It only sits with the landlord as security and comes back with interest if nothing is outstanding. They may deduct three things, no more.
- Unpaid rent or unpaid service charges.
- Genuine damage to the flat that goes beyond normal wear.
- Missing items from the handover record, and keys count as items.
Locks fall under points two and three. And that is exactly where the tricks happen. A landlord who wants to push a cylinder swap on you because the lock is "old" is confusing wear with damage. That is not a small thing. It is the most common wrong deduction I know.
Normal wear is not damage
A lock that sticks a little after eight years is wear, and wear is the landlord's cost. That is what rent is for. A worn cylinder, a stiff latch or fittings gone dull over the years do not belong on your bill. Least of all an "upgrade" to newer technology that you are meant to part-fund without being asked.
Rule of thumb from practice: if the lock still worked when you moved out and you handed back every key, there is nothing to deduct. Nothing at all. An ABUS or BKS standard cylinder easily lasts fifteen years, a good EVVA or Winkhaus even longer. If a thing like that is supposed to be "renewed" after five years of tenancy, ask back why. The answer is usually thin.
The missing key, the classic
This is where the arguments start. If you fail to hand back every key listed in the handover record, you are liable. So far that is fair. But how expensive it gets hangs entirely on one question: does the key belong to a master-key system or not?
Single lock, the simple case
If it is a plain flat, cellar or letterbox key with no central system, the matter is small. Have a copy cut, a few euros, done. A simple key costs 5 to 15 euros to copy, a security key with a security card 25 to 60 euros. The landlord may charge you for the copy, no more. No cylinder swap, no surcharge, no flat rate.
Master-key system, now it gets expensive
But if the key belongs to a master-key system, meaning a setup where one key opens several doors or a grand master is involved, things look different. Here the landlord can demand a swap of the affected cylinders, but only if they can prove security is genuinely at risk. And that is the decisive hurdle. Proof means: it must be concretely possible for someone with the missing key to get in who should not.
Who ends up paying and under what conditions, I have written up in detail in who pays for the lock change. The whole mechanism behind such a system I explain in our piece on the master-key system in an apartment block. Read that before you agree to any demand.
Important, and many people do not know this: even with a master-key system the landlord has to quantify the damage concretely. They cannot simply pick the most expensive option. They have to swap the cylinders that are actually affected, not the whole system in the building just because it is more convenient. And they have to credit a deduction for age and wear. A system that has been hanging for ten years is no longer as good as new, so you do not pay the new price either.
Real prices, so you can judge any demand
So you are not left in the dark, here are the figures from Frankfurt, as of 2026. These are fair values, not emergency-service moon prices.
| Item | Fair range |
|---|---|
| Standard cylinder, material | 15 to 40 EUR |
| Security cylinder ABUS, BKS, Winkhaus | 60 to 150 EUR |
| Fitting per cylinder, labour | 30 to 70 EUR |
| Copy a simple key | 5 to 15 EUR |
| Security key with card | 25 to 60 EUR |
| Full cylinder swap, flat door | around 90 to 220 EUR |
If a landlord wants to deduct 900 euros for a single lost cellar key, this table shows you at a glance that something is off. What an honest lock replacement really costs is laid out clearly with us, and our prices are public, so you can cross-check any invoice.
Locked out and in a hurry?
Price quoted up front, vetted partner business, ~22 minutes on site.
Two cases from the emergency service
A couple of weeks ago a customer in Ostend called me at night: the landlord wanted to deduct 900 euros for a "new locking system" from the deposit over one missing cellar key. We looked at the setup. A plain standard cylinder, no central system, that cellar key opened no other door. A copy would have cost 12 euros. With that assessment in hand he objected, and the 900 euros were off the table.
Last week in Bornheim, the opposite. A tenant had lost a grand master key that opened every flat door in the building and the front door. That was a real security problem. There the system genuinely had to be re-keyed, and the cost fell to her. But only the affected cylinders, with an age deduction, and against a clean invoice. Not 900 euros out of thin air, but a traceable line item. That is the difference. One case was a rip-off, the other was justified.
How to protect your deposit
The whole fight can almost always be settled at move-in and move-out. Whoever documents cleanly at the start holds the better cards at the end.
- Have every key, with quantity, signed off in the handover record, both at move-in and move-out. Two flat keys, one cellar, one letterbox, that gets noted.
- Do not hand back any key "later", hand over all of them at the handover. A promised key is a key not returned, until it arrives.
- Insist on an itemised statement. You do not have to accept flat-rate deductions without a receipt, ask for a tradesperson's invoice.
- Photograph the lock and the keys you hand over at move-out. Date on the photo, that helps.
- If the landlord demands a complete system over a single lost flat key, get advice from the tenants' association. As a member it costs almost nothing and is worth every cent.
What you do not have to accept
- A cylinder swap just because the lock is "old", with no missing key.
- A flat rate without an invoice, the "that will be 300 euros" kind.
- The new price for a system that has been hanging for years, without an age deduction.
- Renewal of the whole system when only one cylinder is affected.
- A demand over the phone with no written breakdown.
Common questions, answered briefly
Do I have to pay if I lost a key but nobody can get in? For a single key with no system: only the copy, a few euros. A cylinder swap only if the key was labelled or the address is known and that creates a risk.
How long may the landlord keep the deposit? Three to six months after move-out is usual, so they can settle the service charges. They may not use an open lock issue as a pretext forever.
What if a deduction has already been made and I think it is wrong? Object in writing, demand a receipt, and if it goes nowhere, go to the tenants' association. In my experience half the wrong deductions collapse after the first clear letter.
Bottom line: count the keys at move-in and move-out, get everything signed off, and check every deduction. A single missing key costs a few euros, not three figures. And if you need a second opinion on a demand, call us, we sort that out on the phone faster than any fight by letter. You will find our contact here.
