immonum is software for sales organisations and property developers who sell flats as investment property (buy-to-let). For each client, it calculates what a flat costs or earns them each month, before and after tax. Reservations, the sales process and commission are handled in the same program.
The demo is a shared account with sample data. You do not need an account to use it. immonum itself is in German. Calculations follow German tax law.
The calculator shows on a small scale what a calculation in immonum looks like. Change the purchase price, equity or interest rate and all values are recalculated immediately. The flat and all starting values are examples. Tax is calculated under German income tax law.
Please enter the purchase price (at least €10,000), floor area and taxable income. Until then, the calculator shows the last valid values.
All values in €.
The calculator is simplified. It uses the 2026 German income tax scale under § 32a EStG (Einkommensteuergesetz, Income Tax Act), without solidarity surcharge and church tax, with one loan plus an optional KfW loan. Rent and costs rise by 2% a year. In the program, immonum also calculates church tax, several loans, special repayments, grants, interest during construction and an income that changes over the years. All results are non-binding model calculations.
Open the demoThe tax effect is the difference between two tax calculations: once without the flat and once with it. For both, immonum uses the German income tax scale under § 32a EStG and the client's details: taxable income, type of assessment (individual or joint) and church tax. A fixed marginal tax rate is not assumed.
The calculation with the flat includes the income from letting: rent minus running costs, minus interest, minus depreciation (AfA, Absetzung für Abnutzung, i.e. depreciation for wear and tear). If this income is negative, the tax falls and the client gets money back. If it is positive, the tax rises.
immonum only uses tax law that has been promulgated. For later years, the most recently adopted tax scale applies, either frozen or projected forward depending on the setting. immonum itself is in German. Calculations follow German tax law.
A sample calculation does not replace tax advice. immonum shows how assumptions affect the result. The adviser is responsible for the assumptions themselves.
Values from the calculator above, first full year, 2026 tax scale.
The demo is a shared account with two sample projects, sample clients and finished calculations. You can click on and change everything. The program and the sample data are in German.
The demo is reset every night at 3 a.m. (German time). Uploads, sending emails, client links, backups and user and account settings are blocked in the demo.
Other people can see what you enter in the demo. Do not enter any real client data there.
A calculation links a client with a flat. You set the project's defaults once: acquisition costs, depreciation, running costs, increases and financing. Every calculation in the project adopts them.
Six steps guide you through the calculation: flat, acquisition costs, rent, buyer, financing and results. A tick shows what is complete.
The PDF carries your company's logo, colour and contact details on the cover page and in every page header. You decide which pages appear and in what order. The PDF is in German.
With a client link, your client sees their calculation in the browser, in your company's design, without needing an account. They can download the PDF there and ask for a call back. You see when the link was opened and can block it at any time. The link is valid for 7, 30 or 90 days.
A project groups the flats of a development together with location, schedule, parking spaces and documents. From there you see for every flat whether it is available, reserved or sold.
Administrators create users and release projects to individual advisers or groups, to view or to edit. Advisers see only released projects and their own clients.
You import contacts from CSV, Excel or vCard. immonum detects possible duplicates. You upload flats as an Excel file or paste them directly from Excel. immonum imports projects from other software via EXP export files and CSV tables.
All lists can be exported as CSV. You can pass a project, including its defaults and flats, to a partner as a file.
immonum is hosted by Host Europe GmbH in Cologne, Germany, under a data processing agreement. The pages do not load any third-party services: no font servers, no analytics tools, no advertising networks.
All figures in the videos are examples. The videos have German audio; English subtitles are switched on by default.
A tour from the project and the flat to the finished sample calculation.
Where to find each area, from the dashboard to administration.
You set the monthly fee yourself. Most customers pay €20 a month. A higher fee goes into the further development of immonum; a lower one is also fine.
The fee applies per company and covers all users in your company. There is no minimum term; you can cancel monthly with effect from the end of the month. Payment is by invoice or SEPA direct debit. Prices are subject to statutory VAT where applicable.
Our terms and conditions (AGB) apply, together with the data processing agreement (AVV). The English versions are convenience translations; only the German versions are legally binding.
immonum is developed and operated by KIWAX Thomas Wachsmuth in Berlin, Germany.
KIWAX Thomas WachsmuthWe are happy to provide references from property sales on request.
You have seen the demo and would like to work with your own projects? Tell us which company the access is for. The program itself is in German.
