Getting married costs a woman on average a fifth of her income, according to the Ifo economic institute, citing its own research.
"The wage gap between men and women increases with marriage," said Elena Herold of Ifo. The gap usually starts to widen a few years after marriage, she added.
Among men, entering into marriage does not produce any changes in salary, unlike among women.
"It's not just about marriage, because it's usually in the first few years after marriage that children come along," Herold said. "Even when we take the effect of children out of the equation, women's wages start to lag behind their husbands'."
Without children, the difference increases to 20 percent, and with children to about half.
This only applies to marriage, not cohabitation. Herold believes this is a consequence of the greater economic security that wives feel in a formal marriage, which encourages many to work with less ambition.
The income gap is not a result of lower wages for women. Hourly earnings have not changed significantly. The growing gap is rather attributable to the fact that many women stop working or work part-time after marriage.
This effect statistically extends over several years. At the same time, a one-fifth lower average salary is accompanied by a one-fifth more work at home, again without children in the calculation.
Among men, such a shift towards housework is not statistically significant.
Ifo experts estimate that women often give up full-time employment due to tax incentives, as the combined salary can move the family into a higher class and higher expenses.
The traditional division of roles also contributes to the growing difference in spouses' earnings, Elena Herold added.
Ifo published the study on Thursday, March 7, International Equal Pay Day.
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