Körperschaftsteuererklärung (Corporate Tax Return)
The annual corporate income tax return for GmbHs and other corporations, covering taxable profit computation and settlement of Körperschaftsteuer at 15% plus the 5.5% Solidaritätszuschlag. Also triggers the Gewerbesteuer-Messbescheid basis and settles any difference between advance payments and final liability.
Who this applies to
- GmbH (Gesellschaft mit beschränkter Haftung)
- AG (Aktiengesellschaft)
- SE (Societas Europaea)
- All other corporations subject to §1 KStG
- Associations and cooperatives with commercial activities
What to file
Körperschaftsteuererklärung (form KSt 1) including: income statement / Handelsbilanz reconciliation, Anlage GK (income from commercial activity), Anlage ZVE (income computation), Anlage WA (start/end values), Anlage AEV (income adjustments), and signed tax balance sheet (Steuerbilanz) or reconciliation statement
How to file
Electronically via ELSTER (www.elster.de) — paper filing not accepted for corporations since 2011. Returns are authenticated using an ELSTER organisation certificate (Organisationszertifikat) or via a Steuerberater's authentication.
Payment due
Advance payments quarterly on 10 March, 10 June, 10 September, 10 December based on prior year's liability. Final payment (or refund) within one month of the tax assessment notice (Steuerbescheid).
Penalties for missing this deadline
Late filing surcharge (Verspätungszuschlag) of up to 10% of tax assessed or a minimum of €25, capped at €25,000 per return. The Finanzamt may also estimate tax (Schätzung) and issue an assessment based on estimated higher profits.
Filing checklist
- Annual accounts (Jahresabschluss / Handelsbilanz) signed by managing director
- Steuerbilanz or reconciliation from HGB to Steuerbilanz prepared
- Advance payment history confirmed and reconciled
- All income adjustments under §8 KStG documented (e.g., non-deductible expenses, verdeckte Gewinnausschüttungen)
- ELSTER authentication credentials available (organisation certificate or Steuerberater access)
Documents you'll need
- Signed Jahresabschluss (Bilanz + GuV + Anhang if applicable)
- Director's report (Lagebericht) if required by company size
- Gesellschafterbeschluss adopting the annual accounts
- Evidence of all Betriebsausgaben claimed (receipts, contracts, payroll records)
Common mistakes to avoid
- Filing commercial accounts without making required Steuerbilanz adjustments — particularly the non-deductibility of Gewerbesteuer
- Forgetting the Anlage WA (beginning and end net asset values) when submitting
- Missing quarterly advance payments, which attracts interest even if the annual return is filed on time
- Confusing the KSt deadline with the Gewerbesteuer deadline — they are different returns filed with different bases
Never miss a Germany deadline
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