Methodology
How netleft calculates — and why you can trust the numbers.
The official basis
The income-tax calculation implements the official Programmablaufplan (PAP) published by Germany's Federal Ministry of Finance (BMF) for 2026 — the same algorithm payroll software uses. No approximation, no rule of thumb: the §32a EStG tax tariff, the Vorsorgepauschale, and every add-on and deduction follow the official procedure.
Validated to the cent
The engine is checked against the official BMF Prüftabelle — to the cent, across all six Steuerklassen. 108 of those reference cases run as automated tests, inside a suite of 365 tests that runs on every change. If a single cent is off, the build fails.
Social insurance, 2026
The parameters come from the official 2026 values (Sozialversicherungs-Rechengrößenverordnung):
- Ceiling — pension / unemployment (BBG)€101,400
- Ceiling — health / long-term care (BBG)€69,750
- Bezugsgröße (monthly)€3,955
- Minimum contribution base (monthly, ≈ Bezugsgröße ÷ 3)€1,318
These values are shown live from the engine constants — the same source the calculators use.
The self-employed engine
The Freiberufler and Gewerbe calculation is grounded in statute, with section references: the §32a EStG income-tax tariff, Vorsorgeaufwendungen under §10 EStG (including the 4% reduction under §10 Abs. 1 Nr. 3a Satz 4 EStG when there is a Krankengeld entitlement), Gewerbesteuer with the §35 EStG credit, voluntary GKV under §243 SGB V (ermäßigter Satz), KSK compulsory insurance under §5 Abs. 1 Nr. 4 SGB V with Krankengeld from the 7th week (§46 SGB V), Verlustvortrag under §10d EStG, and Progressionsvorbehalt under §32b EStG.
Every figure is computed, not typed
Every euro amount on this site — in the calculators, the guides, and the FAQs — is computed at build time by the same engine. There are no hand-typed example numbers: change an official parameter and every example updates with it automatically.