Number format: this calculator uses German notation throughout — a comma is the decimal separator and a dot groups thousands. “1.234,56” means one thousand two hundred thirty-four euros and fifty-six cents. The figures come from German tax law, so they are shown the way German authorities write them.
One-off payment (sonstiger Bezug)
One-off payments such as a 13th salary or a bonus, taxed by the annual-scale method, not like regular pay.
In plain language
If you receive a one-off payment on top of your normal salary — a Christmas bonus, a 13th salary, a bonus — the tax office treats it differently from your monthly pay. The reason: it assumes your annual income has risen by that amount and asks how much tax would be due on that higher annual income. The difference from the tax without the payment is the tax on the bonus. Because your tax rate rises with income, proportionally less of the bonus survives than of your normal salary. That is not a mistake and not a penalty tax — the tax return settles it exactly this way.
In detail
Under § 39b (3) EStG the wage tax on a one-off payment is determined as the difference between two annual wage tax amounts: one on the expected annual wage without the payment, one with it. The official program flow chart models this through the inputs JRE4 (annual wage) and SONSTB (one-off payment) and returns STS, SOLZS and BKS. In social security law § 23a SGB IV applies: the one-off payment attracts contributions to the extent that the pro-rata annual assessment ceiling has not already been used up by the regular pay — on high salaries it therefore stays wholly or partly free of contributions.
Worked example
4.000 € monthly pay (tax class I, North Rhine-Westphalia, statutory health insurance) and a 13th salary of 4.000 €: the bonus attracts 996 € of wage tax — 24,9 %, whereas the regular monthly pay bears only 13,1 % on average. Social security under § 23a SGB IV is added, because an annual wage of 48.000 € does not yet exhaust either assessment ceiling. At 10.000 € monthly pay the contribution room would be exhausted — then no social security at all falls on the one-off payment.
In brief
Wage tax is the difference between annual wage tax with and without the payment; contributions only up to the pro-rata ceiling.
Legal basis: § 39b Abs. 3 EStG, § 23a SGB IV · as at 2026