How does marriage affect tax class in Germany?

Marriage in Germany unlocks several tax-class options. After the marriage is registered, the Finanzamt usually moves both spouses to class 4 by default; from there, you can pick between three combinations.

Class 4/4 applies the same withholding rules as for singles to both partners. It works well when both incomes are similar.

Class 3/5 favours the higher earner with low monthly withholding (class 3) and over-withholds the lower earner (class 5). The annual tax for the household is similar to 4/4, but monthly cash flow shifts noticeably towards the higher earner.

Class 4 with factor (Faktorverfahren) keeps both partners at 4 but applies a calculated factor to even out monthly net pay so the year-end true-up at the tax return is small.

Marriage also unlocks the Zusammenveranlagung (joint tax assessment) at year-end, which is usually beneficial when the incomes differ — sometimes meaningfully so.

There is one situation where the choice really starts to matter: parental leave. Elterngeld is calculated on the lower-leave-taking partner's net pay from the months before the leave, so a tax-class change planned several months in advance can directly increase the Elterngeld amount. This is not a hack — the rules are designed this way — but it requires planning rather than just leaving the default.

The point is simply that the default rarely happens to be the optimal choice for a given couple. It is worth a quick review after marriage and again before any major life event.