German chancellor Angela Merkel voted against treating gay couples equally with straight partners in tax law.
The chairwoman sided with the majority of Christian Democratic Union members who favored protecting traditional marriage and family during the party's two-day congress in Hannover.
The motion to modernize the party's policies was flatly rejected after a heated debate on the thorny issue.
Commenting on her decision not to support the law change, Merkel explained she 'sees marriage directly linked to the family and both are under the special protection of the state.'
However, 1,000 delegates supported instead a compromise motion which acknowledged the values of same-sex partnerships but rejected equal tax treatment.
'God created us humans as woman and man, and I think he thought there was something in that,' Steffen Flath, the head of the CDU group in Saxony state, told the congress, reported The Local.
The country's top court is expected to weigh in on the constitutionality of tax inequality before the end of 2013.
Same-sex couples in the EU country can currently become registered life partners, giving rights and obligations in areas such as inheritance, alimony, health insurance, immigration and name change but not tax benefits.
A change in law would mean gay couples whose incomes vary significantly would be able to pool their salaries when calculating their tax bills.