NULLPOINTER Nullpointer Labs / Apps / Nebenkosten App
Nebenkosten App
A Nullpointer Labs product
The utility cost statement, without the dread.
Once a year, landlords across Germany, Austria and Switzerland sit down with a pile of invoices, a set of meter readings and a spreadsheet that stops adding up somewhere around the third distribution key. The Nebenkosten App turns that into a guided flow: nine steps, one check at the end, and a PDF you can send a tenant without flinching.
// the problem
Why this hurts every single year
A German utility cost statement is not a sum. Every cost item carries its own distribution key — floor area, number of occupants, units or metered consumption. Meters have to line up with the billing period, a tenant who moved in mid-year has to be prorated, advance payments are set against the total, and since 2023 the CO₂ cost split has to be divided between landlord and tenant according to the building's efficiency band.
On top of that, the tenant is entitled to check every single line and has twelve months to do it. A mistake does not just cost nerves; it can cost money. The deadline for issuing the statement is just as unforgiving.
That is why the app is not a calculator with a few fields, but a flow that fixes the order of the work and checks the result before it lets you export it.
// features
What the app takes off your desk
From tenant details to a signature-ready PDF — and then into an archive, so last year's statement is still there when someone asks.
Guided flow
Nine steps in a fixed order: tenant, billing period, advance payments made, distribution keys, cost items, meters, CO₂ split, new advance payment, details. Each step shows whether it is complete.
Distribution keys
Floor area, occupants, units or metered consumption — chosen per cost item, with custom keys you can define once and reuse as the default next year.
Meters & readings
Cold and hot water, heating, shared electricity. Opening and closing readings, interim readings on tenant change, prorated across the period.
CO₂ cost split
The German split between landlord and tenant by building efficiency band is built in and shown transparently in the PDF.
AI check before export
A pass over the whole statement before the PDF exists: missing items, implausible amounts, unassigned meters, periods that do not line up.
A PDF you can send
Cost breakdown, charts, CO₂ disclosure and a signature field — in the layout tenants recognise from professional statements.
Several properties
Single flats, apartment buildings and commercial units side by side, sorted into folders. Properties you have sold move to the archive instead of being deleted.
Sync, archive & export
Automatic sync between devices, finished statements kept read-only in the archive, and a GDPR-compliant JSON export of your own data.
DE · AT · CH
German Betriebskostenverordnung, Austrian MRG and Swiss practice, plus templates for the United States and the UAE — including each country's number and date formats.
// platforms & pricing
Wherever you happen to be
The app runs on iPhone and iPad, on Android and in the browser — same data, synced automatically. You collect the invoices across the year anyway; the statement itself gets made wherever it suits.
Creating a statement is free; export and printing are locked in the free version. For the finished PDF there are yearly plans for landlords and for property managers, plus a one-time unlimited licence with no subscription. Current pricing is on the product website.
The interface is German — which is the point, given who the statement has to convince.
// questions
Frequently asked
What is a Nebenkostenabrechnung?
It is the annual utility cost statement a landlord in the German-speaking world owes their tenant: a line-by-line account of heating, water, waste, caretaker and other running costs, each split by an agreed distribution key and set against the advance payments the tenant already made. In Germany the rules come from § 556 BGB and the Betriebskostenverordnung, in Austria from the MRG.
Who is the Nebenkosten App for?
Private landlords with one or a handful of flats, and property managers with several buildings. Single flats, apartment buildings and commercial units can be run side by side.
Which countries and legal frameworks does it cover?
It is built around § 556 BGB and the German Betriebskostenverordnung, supports Austrian statements under the MRG and Swiss practice, and ships templates for the United States and the UAE as well. The German CO₂ cost split between landlord and tenant is included.
What does the AI check before the PDF?
It runs over the whole statement before the PDF is produced, looking for completeness and plausibility: missing items, unusual amounts, meters that have not been assigned, periods that do not line up. It is not legal advice — it catches the mistakes a tenant would otherwise find first.
Which devices does the Nebenkosten App run on?
iPhone and iPad via the App Store, Android via Google Play, and any browser as a web app at app.nebenkosten-app.de. Data is synchronised between devices.
Note: the Nebenkosten App helps you produce a statement; it does not replace legal or tax advice.
// nullpointer labs
Built by Nullpointer Labs
We designed the Nebenkosten App, built it, shipped it to both stores and still run it. If you have something similar in mind — a specialist product with legal weight that has to work on iOS, Android and the web — let's talk.