The Costs Nobody Lists: What Actually Lands on the Owner

The fantasy is "€600 rent minus €878 mortgage = €278/month." Reality has a third column.

The tenant's Nebenkostenvorauszahlung covers only umlagefähige items under the BetrKV: heating, water, waste, cleaning, building insurance, Hausmeister. Of a €230/month Hausgeld, roughly €140 is recoverable. The remaining €90 is yours, permanently, and appears in no listing.

Annual non-recoverable budget for our 58 m² flat:

These are not pessimistic – they are the official numbers. §28 II. BV sets 2026 maintenance allowances at €11.50/m²/year under 22 years old, €14.58 at 22+, and €18.62 at 32+. A 1970s block sits in the top band: €18.62 × 58 = €1,080/year for maintenance alone, which is exactly what Rücklage plus Sondereigentum add to above. §29 II. BV puts Mietausfallwagnis at 2% of gross rent. The 2026 Verwaltungskosten allowance is €372.46 per unit per year.

Four traps specific to a WEG:

• A Sonderumlage is not covered by the reserve. Ask for the current Rücklage balance and divide by total m². Under roughly €25/m² on a 50-year-old building means the next roof comes out of your pocket.
• Read the last three Protokolle and the Beschlusssammlung before you fall in love, not after. A resolved-but-unbilled façade job is a price negotiation (see the negotiation article); discovered later it is just a bill.
• A block recently converted to Wohnungseigentum usually has a near-empty reserve.
• Legal costs inside a fractious WEG are real and uncapped.

Corrected monthly maths: €600 − €878 − €142 = −€420/month pre-tax, about −€258 after the tax shield. Budget €260/month of permanent negative carry, not €278 of income. Being wrong by €540/month, every month, is the single most common amateur error in German buy-to-let.