Our sources and how we check figures

Which sources we use

For Berlin, we work with the bodies that collect or publish prices, land values and rents. The figures of the Berlin valuation committee (Gutachterausschuss für Grundstückswerte in Berlin) are based on the purchase contracts concluded before a notary, not on listings. Which source stands for what, and where you can find an example on our website:

We link to legislation where the federal government and the states publish it themselves: federal law on gesetze-im-internet.de, Berlin state law on gesetze.berlin.de and Brandenburg state law in the BRAVORS legislation system.

How we present figures

Every market figure carries its source and as-of date, i.e. the date of the analysis or of retrieval. This lets you look the figure up in the source and see how old it is.

We distinguish between two kinds of price. Asking prices are prices that sellers ask for in listings; the Housing Market Report of Investitionsbank Berlin is based on such listings. Purchase prices are the amounts from notarised purchase contracts, as analysed by the valuation committee. That is why the page on the price-to-rent multiplier shows values from completed sales and values from listings separately.

We label values that we calculate ourselves from sources as ‘own calculation’ or ‘calculated’ and explain how they were calculated. For example, we determine the price-to-rent multiplier for each district from the median asking price per square metre divided by twelve monthly rents per square metre. If a value is missing from a source, the row stays empty. We do not estimate it. We do not make price forecasts.

How we check

Every guide page we have written since 3 October 2026 goes through a fixed check before publication. First, we read every figure and every cited legal provision against the source. A check script records the verified values and raises an alert if one of them is missing from the text; worked examples are recalculated by script. It also retrieves every source link on the page. If a source cannot be reached, the check counts as failed. Formal points are checked too, such as the as-of date and the mandatory information in the page footer, and every internal link must lead to an existing page.

Once a week, an automated run retrieves all external source links on the website. If a source has disappeared or its server responds with an error, the run reports the link to us. It cannot tell whether the figure behind a reachable link is still current. For that, we review the market data every quarter and update it as soon as a source publishes new figures; the Bundesbank interest rate series is updated each time the website is rebuilt.

What we do not do

Our guides are intended for initial guidance and do not replace legal or tax advice in individual cases. As estate agents, we may not and do not wish to provide legal advice; our assessments are not market value reports (Verkehrswertgutachten). Such a report is written by qualified valuation experts or by the Berlin valuation committee (Gutachterausschuss für Grundstückswerte in Berlin).

A value assessment from us is also not a price guarantee. What a buyer ultimately pays depends on the property, the location and the market situation. The page Property valuation Berlin describes how our free assessment is produced.

As-of date and reporting errors

Every guide page states its as-of date; this one reflects the position as of 10 October 2026. If a figure does not match the source, is out of date or a link leads nowhere, write to us via the contact page or at info@bbi-immobilien.de. Please name the page and the passage.

Sources

• Berlin valuation committee (Gutachterausschuss für Grundstückswerte in Berlin), market information
• Valuation committee (Gutachterausschuss): Berlin Property Market Report 2025/2026, purchase prices from notarised contracts
• Valuation committee (Gutachterausschuss): standard land values, reference date 1 January
• BORIS Berlin, standard land values by zone
• Investitionsbank Berlin: Housing Market Report 2025, asking prices and asking rents
• Berlin rent index (Mietspiegel), local reference rent, residential location ratings
• Senate Department for Urban Development, Building and Housing: social preservation law, Milieuschutz
• Senate Department for Urban Development, Building and Housing: ban on the misuse of residential space, permits, legal position
• Service Berlin, services of the Berlin administration
• Statistical Office for Berlin-Brandenburg, population, housing, construction activity
• Deutsche Bundesbank: banks' effective interest rates on new business, interest rates on housing loans
• Valuation committees (Gutachterausschüsse) in the state of Brandenburg, property market reports
• BORIS Land Brandenburg, standard land values in the area around Berlin
• Gesetze im Internet, federal law
• Berlin legislation and case law database (gesetze.berlin.de), Berlin state law
• BRAVORS, Brandenburg legislation system, Brandenburg state law

All links accessed on 10 October 2026.