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.
Choice of tax class (Steuerklassenwahl)
It does not change the tax owed for the year, only the monthly amount withheld.
There is a full article on this term: Tax classes explained
In plain language
Married couples in Germany can choose how their monthly wage tax is split between them. The key point: at the end of the year they owe the same amount whichever they choose. The choice only shifts when the money moves. III/V gives the higher earner more net pay each month — and often ends in a payment due. The factor method comes closest to the actual liability, but requires an application to the tax office.
In detail
The combination of tax classes determines only the size of the monthly wage tax deduction, not the annual liability: under joint assessment that follows from the splitting procedure of § 32a (5) EStG and is independent of the class chosen. III/V assumes that the partner in class V uses practically no allowances; that produces high net pay for one and a very high deduction for the other. The factor method of § 39f EStG multiplies the wage tax from IV/IV by the factor Y/X — the ratio of the expected annual tax to the sum of the wage tax under IV/IV — and thereby splits the deduction in proportion to the incomes. Where both spouses receive wages and choose III/V or the factor method, they must file a tax return (§ 46 (2) no. 3a EStG). The factor method likewise requires that both receive wages (§ 39f (1) sentence 1 EStG). The factor produced by this calculator has not been checked against an official source — only the factor entered by the tax office is binding.
Worked example
Two spouses earning 5.000 € and 1.500 € gross a month, both aged 35, no children, statutory health insurance: the annual liability is 8.518,00 € in every variant. III/V gives 4.577,67 € of net pay a month but ends with 1.862,08 € to pay. IV/IV withholds too much — a refund of 981,92 €. IV/IV with the factor works with a factor of 0,880 and lands within 159,04 € — it comes closest to the liability. If only one spouse earns (5.000 € and 0 €), tax class III matches the annual liability almost exactly; the factor method is not available then.
In brief
III/V gives the higher earner more net pay but usually ends in a payment due. The factor method spreads the deduction by Y : X.
Legal basis: § 38b EStG, factor method § 39f EStG · as at 2026