How much rent may I charge?

Three questions — one permitted rent

Before you re-let a flat or send a rent increase, run through the following three-step check:

Step 1: existing tenancy or new letting?

Existing rent: Rent increase during an ongoing contract — capping limit 15–20% over 3 years (German Civil Code), 15-month interval since the last increase, written justification using the rent index/comparable flats/an expert appraisal.

New letting: First letting or change of tenant — the rent cap only applies where the federal state has decreed it (~410 cities). In areas without a rent cap, the rent is, in principle, freely negotiable — BUT not more than 50% above the local reference rent (§5 WiStG: rent profiteering).

Step 2: rent cap — does it apply?

Check on your state government's website whether your town/municipality is listed in the rent-limitation ordinance. Examples:

• Berlin: entire city area since 2015, extended until 2029
• Hamburg: gesamtes Stadtgebiet
• Munich, Augsburg, Regensburg: yes
• Düsseldorf, Köln, Bonn, Aachen: yes (NRW ordinance)
• Frankfurt, Wiesbaden, Darmstadt, Offenbach: ja (Hessen)
• Stuttgart, Heidelberg, Tübingen, Freiburg: yes (BW ordinance)
• Leipzig, Dresden, Görlitz: NO (Saxony has no ordinance)

In a rent-cap area: new lettings at most 10% above the local reference rent (§556d BGB). Exceptions: new build from 10/2014, extensive modernisation in the last 3 years.

Step 3: determine the local reference rent

Three ways to determine the reference rent:

• a) Qualified Mietspiegel (e.g. Berlin, London, Munich) — carries evidential weight in court
• b) Simple Mietspiegel — treated by the court as an indication
• c) Three comparable flats (same size, location, fittings) — from advertisements or your own portfolio
• d) Expert appraisal (~800–2,000 €) — for complex or special flats

Calculation example: 75 m² apartment in Köln-Sülz

• Cologne Mietspiegel 2024 (year built 1955-1969, average location, with bathroom): 9.80 €/m² average value
• Spanne: 8,20–11,40 €/m²
• Rent cap (Mietpreisbremse) active (North Rhine-Westphalia): max. 9,80 × 1,10 = 10,78 €/m²
• For 75 m², the maximum permissible net cold rent for re-letting: 808.50 € (instead of 855 € at the upper range value)
• Rent profiteering threshold (50% above the average): 14,70 €/m² → criminally relevant from 1.103 €/month

Caution: these mistakes really cost money

• Rent cap (Mietpreisbremse) ignored: the tenant can reclaim rent retrospectively (up to 2.5 years)
• Index or graduated rent miscalculated: the entire contract may become void
• Rent increase without justification by the Mietspiegel: formally void, the tenant does not have to consent
• Furnishing surcharge applied as a flat sum: only permitted on a percentage basis, otherwise the rent cap (Mietpreisbremse) is circumvented

How Rentprime helps you

The Rentprime rent-increase assistant automatically checks: the 15-month interval, the capping limit (depending on the region), the current rent-index value (from Q3 2026 for 80 cities), BGB-compliant justification text, and dispatch by registered post with proof of delivery.