betriebskostenabrechnung

/mietrecht:betriebskostenabrechnung

Purpose

The operating cost statement is the most common cause of disputes in tenancy law and the one with the harshest preclusive time limits: anyone who misses the 12-month accounting deadline loses the supplementary claim permanently; any tenant who misses the 12-month objection period can no longer object to substantive errors. This skill consistently separates formal errors (which render the statement invalid as a whole) from substantive errors (which only correct the balance) and calculates the time limits deterministically.

Inputs

• Tenancy agreement: cost allocation agreement, agreed allocation key, amount of advance payments
• Statement in its wording, date of receipt, accounting period
• Total costs per cost type, total allocation key, tenant's share, advance payments made
• Heating cost statement (consumption / floor area distribution, meter reading records)
• Information on building energy efficiency (for the CO2 tier model)
• Vacancy during the accounting period, change of user, commercial co-use
• Whether inspection of receipts was requested or granted

Sub-agent architecture

The examination is carried out in prose by specialised steps; this skill deliberately does not include an agentsblock is deliberately omitted by this skill (mietrecht convention). A time-limit checker first establishes whether the accounting and objection periods have been observed — this determines whether a substantive examination can still change anything at all. A formal checker checks the minimum details of the statement; a formal error renders it invalid as a whole and the supplementary claim is not due. A substantive checker examines the allocability of each cost type, the allocation keys, economic efficiency and the heating cost distribution. A CO2 checker separately handles the tier model of the CO2KostAufG. A receipt checker organises the inspection and the right of retention.

Procedure

1. Cost allocation agreement and obligation to render accounts (§ 556(1), (3) sentence 1 BGB)

Operating costs are only allocable if the parties have agreed this; without an agreement they are covered by the basic rent. Reference to the Operating Costs Ordinance or to "operating costs within the meaning of § 556(1) BGB" is sufficient. Advance payments must be accounted for annually; the accounting period may not exceed twelve months. Not allocable are administrative costs and Maintenance/repair costs (§ 1 (2) BetrKV).

2. Operating cost catalogue (§ 2 BetrKV)

The catalogue in § 2 BetrKV is conclusive for the types named therein; No. 17 ("other operating costs") covers further ongoing costs only if they are specifically named in the lease agreement. A blanket clause "and other operating costs" is not sufficient for this. Check each item individually: property tax, water/sewage, heating, hot water, elevator, street cleaning, waste removal, building cleaning, garden maintenance, lighting, chimney sweeping, property and liability insurance, caretaker, communal antenna, laundry care.

3. Billing period (§ 556 (3) sentences 2, 3 BGB)

The statement of account must be communicated to the tenant at the latest by the end of the twelfth month after the end of the billing period . After this period expires, the assertion of a additional payment claim is excluded, unless the landlord is not responsible for the late assertion (sentence 3). This is a substantive preclusive period — it operates only against additional payment claims; a credit balance must be paid out even if the statement of account is late, and the tenant's claim to be issued the statement of account continues to exist. What is decisive is the receipt of the statement of account, not the sending.

4. Formal requirements — minimum information

A formally proper statement of account must be comprehensible in thought and calculation for an average tenant and contains:

1. Compilation of the total costs per cost type,
2. Statement and explanation of the distribution key,
3. Calculation of the tenant's share,
4. Deduction of the advance payments,
5. made, statement of the billing period.

A formal error renders the statement of account invalid as a whole; the additional payment claim does not become due, and after expiry of the billing period it is definitively lost. A substantive error (wrong approach, calculation error, non-apportionable item) leaves the statement of account effective and leads only to correction of the balance — it can also be corrected in the tenant's favour after the period expires. On the requirements for stating the total costs and for deductions in advance: BGH, judgment of 20 January 2016 – VIII ZR 93/15, https://dejure.org/dienste/vernetzung/rechtsprechung?Gericht=BGH&Datum=2016-01-20&Aktenzeichen=VIII%20ZR%2093/15.

5. Objection period (§ 556 (3) sentences 5, 6 BGB)

The tenant must communicate objections to the statement of account at the latest by the end of the twelfth month after receipt of the statement of account. After the period expires, the tenant can no longer assert objections, unless the tenant is not responsible for the late assertion. The period runs independently of the landlord's billing deadline and is the sharpest pitfall on the tenant's side. Purely formal defects and the question of due date are not subject to preclusion.

6. Allocation key (§ 556a BGB)

Without a deviating agreement, operating costs are to be allocated according to the share of living space . Costs that depend on a recorded consumption are to be allocated according to consumption (§ 556a para. 1 sentence 2 BGB). The landlord can switch to a consumption-based allocation key by declaration in text form ; the switch takes effect at the beginning of the following billing period (para. 2). For heating and hot water , the HeizkostenVapplies with priority: at least 50%, at most 70% according to recorded consumption; in the event of a violation, the tenant has a right of reduction under 15 % (§ 12 HeizkostenV).

7. Principle of economic efficiency (§ 556 para. 3 sentence 1 half-sentence 2 BGB)

The landlord must observe the principle of economic efficiency . He may only charge costs that a reasonable landlord would have incurred with appropriate consideration of the tenant's interests. The tenant who asserts a violation must present specific indications (for example, a clear exceeding of the local operating cost index); only then does the landlord bear a secondary burden of presentation.

8. Inspection of receipts and right of retention

The tenant can demand inspection of the billing documents ; the claim follows from § 259 BGB in conjunction with § 242 BGB. It also extends to the payment receipts (BGH, judgment of 09.12.2020 – VIII ZR 118/19, https://dejure.org/dienste/vernetzung/rechtsprechung?Gericht=BGH&Datum=2020-12-09&Aktenzeichen=VIII%20ZR%20118/19). The place of inspection is regularly the landlord's office; copies only against reimbursement of costs, unless travel is unreasonable. Until inspection is granted, the tenant has a right of retention under § 273 BGB with respect to the additional payment.

9. CO2 cost allocation (CO2KostAufG, since 01.01.2023)

The CO2 price attributable to the fuel under the BEHG is no longer passed on entirely to the tenant. For residential buildings, a tiered model applies based on the building's specific CO2 emissions in kg CO2/m² living space per year: the worse the building's energy performance, the higher the share to be borne by the landlord (up to 95%); with very good efficiency, the tenant bears the full share. Practical requirements:

• The landlord must state the CO2 costs in the billing and present the allocation according to the tiered model in a comprehensible manner; the necessary information is provided by the fuel supplier's invoice.
• If he fails to make the allocation, the tenant may [deduct] the share of heating costs attributable to him by 3 % reduce.
• For non-residential buildings , an equal split applies until further notice.
• In the case of legal restrictions on energy-efficient refurbishment (monument protection, milieu protection), the landlord's share may be reduced.

The specific threshold levels and percentages must be checked against the current statutory text before each billing.

Deterministic calculation

Both one-year periods under § 556(3) BGB are event-based periods under § 187(1) BGB with the period ending pursuant to § 188(2) BGB; § 193 BGB postpones the end to the next working day. The calculator in ../../../scripts/legal_calc/ performs only the arithmetic — the end of the billing period and above all the receipt of the statement remain legal inputs and must be proven separately.

# Abrechnungsfrist § 556 Abs. 3 S. 2 BGB: Abrechnungszeitraum endet 31.12.2025
python -m scripts.legal_calc.cli frist --ereignis 31.12.2025 --menge 12 --einheit monate --land BE

# Einwendungsfrist § 556 Abs. 3 S. 5 BGB: Abrechnung zugegangen am 15.01.2026
python -m scripts.legal_calc.cli frist --ereignis 15.01.2026 --menge 12 --einheit monate --land BE

# Umstellung des Umlagemaßstabs § 556a Abs. 2 BGB: Wirkung zum nächsten Zeitraum
python -m scripts.legal_calc.cli frist --ereignis 31.12.2026 --menge 1 --einheit monate --land BE

--json provides the calculation steps together with the citation of the provision. The calculator says nothing about whether the landlord is responsible for the delay (§ 556(3) sentence 3 BGB) — that remains a question of assessment.

Sources

Statutes

• § 556 BGB, § 556a BGB, § 259 BGB, § 273 BGB, § 242 BGB
• BetrKV — § 1 BetrKV, § 2 BetrKV
• HeizkostenV — § 7 HeizkostenV, § 12 HeizkostenV
• CO2KostAufG (Carbon Dioxide Cost Allocation Act, since 01/01/2023)
• § 187 BGB, § 188 BGB, § 193 BGB

Commentaries

• Langenberg, in: Schmidt-Futterer, Mietrecht, 15th ed. 2023, § 556 BGB marginal no. 1 et seq.
• Zehelein, in: MüKoBGB, 9th ed. 2023, § 556 marginal no. 1 et seq.; § 556a marginal no. 1 et seq.
• Weidenkaff, in: Grüneberg, BGB, 84th ed. 2025, § 556 marginal no. 1 et seq.
• Wall, Operating Costs and Heating Costs Accounting, current edition (practical handbook)

Case law

• BGH, judgment of 20/01/2016 – VIII ZR 93/15 (formal requirements for the operating cost statement; no disclosure of the calculation steps in the case of prior deduction) — verified: https://dejure.org/dienste/vernetzung/rechtsprechung?Gericht=BGH&Datum=2016-01-20&Aktenzeichen=VIII%20ZR%2093/15
• BGH, judgment of 09/12/2020 – VIII ZR 118/19 (tenant's right to inspect payment receipts) — verified: https://dejure.org/dienste/vernetzung/rechtsprechung?Gericht=BGH&Datum=2020-12-09&Aktenzeichen=VIII%20ZR%20118/19
• Regarding the scope of the economic efficiency principle and the burden of proof for the operating cost index, the relevant BGH case law must be consulted [unverifiziert - prüfen].

Drafting aid — tenant's objection letter

Sehr geehrte Damen und Herren,

gegen Ihre Betriebskostenabrechnung für den Zeitraum <…> vom <Datum>,
mir zugegangen am <Datum>, erhebe ich innerhalb der Frist des
§ 556 Abs. 3 S. 5 BGB folgende Einwendungen:

1. Formelle Mängel: Die Abrechnung weist den Verteilerschlüssel für die
   Position <…> nicht aus und ist insoweit nicht nachvollziehbar. Die
   Nachforderung ist daher nicht fällig.
2. Nicht umlagefähige Positionen: Die Position <…> betrifft
   Instandsetzungsaufwand und ist nach § 1 Abs. 2 Nr. 2 BetrKV nicht
   umlagefähig. Die Position "sonstige Betriebskosten" ist im Mietvertrag
   nicht konkret benannt (§ 2 Nr. 17 BetrKV).
3. Heizkosten: Der Verbrauchsanteil beträgt lediglich <…> % und
   unterschreitet die Mindestquote des § 7 HeizkostenV. Ich kürze den
   Heizkostenanteil gemäß § 12 Abs. 1 HeizkostenV um 15 %.
4. CO2-Kosten: Eine Aufteilung nach dem Stufenmodell des CO2KostAufG ist
   nicht ausgewiesen. Ich kürze den Heizkostenanteil um weitere 3 %.
5. Belegeinsicht: Ich beantrage Einsicht in sämtliche Abrechnungsunterlagen
   einschließlich der Zahlungsbelege und schlage den <Datum> vor. Bis zur
   Gewährung mache ich von meinem Zurückbehaltungsrecht nach § 273 BGB
   Gebrauch.

Mit freundlichen Grüßen

Output format

BETRIEBSKOSTENABRECHNUNG — Prüfung — <Mandat-ID> — <Datum>

I.    Umlagevereinbarung (§ 556 Abs. 1)   [vorhanden / fehlt ❌]
II.   Fristen
      - Abrechnungszeitraum               <von> – <bis>
      - Abrechnungsfrist (12 Monate) Ende <Datum>   [gewahrt / versäumt]
      - Zugang der Abrechnung             <Datum>
      - Einwendungsfrist Ende             <Datum>   [offen / abgelaufen]
III.  Formelle Prüfung                    [✅ / ❌ — Abrechnung insgesamt unwirksam]
      - Gesamtkosten je Kostenart         [✅ / ❌]
      - Verteilerschlüssel angegeben      [✅ / ❌]
      - Anteilsberechnung                 [✅ / ❌]
      - Vorauszahlungen abgezogen         [✅ / ❌]
IV.   Materielle Prüfung je Position      <Tabelle: Position | Betrag | umlagefähig? | Rüge>
      Nicht umlagefähig gesamt            <Betrag>
V.    Umlagemaßstab (§ 556a)              [Fläche / Verbrauch / Einheiten]  [✅ / ⚠️]
VI.   Heizkosten (HeizkostenV)            Verbrauchsanteil <…> %  [50–70 % / Verstoß]
      Kürzung § 12 HeizkostenV            [keine / 15 %]
VII.  CO2KostAufG (Stufenmodell)          Vermieteranteil <…> %  [ausgewiesen / fehlt]
      Kürzung bei fehlender Aufteilung    [keine / 3 %]
VIII. Wirtschaftlichkeitsgebot            [kein Anhalt / Rüge <Position>]
IX.   Belegeinsicht                       [gewährt / verlangt am <Datum>]
      Zurückbehaltungsrecht § 273 BGB     [ja / nein]
X.    Korrigierter Saldo                  Abrechnung: <Betrag>
                                          Korrigiert: <Betrag>  [Nachzahlung / Guthaben]

Ergebnis: <Nachforderung fällig / nicht fällig / ausgeschlossen>
Risiko: [🟢 / 🟡 / 🔴]

Risks / typical errors

• Billing deadline missed — the subsequent claim is definitively excluded under § 556(3) sentence 3 BGB; a credit balance must nevertheless be paid out.
• Objection deadline missed — the tenant can no longer object to substantive errors; formal defects and the question of due date remain unaffected by this.
• Formal and substantive errors confused — only the formal error renders the statement as a whole ineffective; anyone who treats both the same gives away items or overestimates the effect of an objection.
• Receipt instead of dispatch — for both deadlines, receipt is what counts; without proof of receipt, the deadline is not substantiated.
• Non-apportionable items — administrative and repair costs (§ 1(2) BetrKV) as well as "other operating costs" not specifically named (§ 2 No. 17 BetrKV).
• Heating cost allocation below 50% consumption — triggers the 15% reduction right under § 12 HeizkostenV.
• CO2 costs not apportioned according to the tiered model — tenant's right to a 3% reduction; the tier thresholds must be checked against the current CO2KostAufG before every statement.
• Inspection of receipts refused — the tenant may withhold the additional payment under § 273 BGB; the additional claim becomes de facto unenforceable.
• Vacancy costs passed on to the tenant — the landlord bears the vacancy share itself.