FRANKFURT—German households are among the poorest—on paper, at least—in the euro zone, according to a study by the European Central Bank that adds a new twist to the debate over how far taxpayers in Northern Europe should go to support weaker countries.

The ECB's findings, released Tuesday, don't give the full picture of a society's living standards, which are affected by things like social protection and infrastructure as well. It also is based primarily on data from 2009 and 2010—early days in the still-festering euro crisis.

Most significantly, the report doesn't adjust for differing rates of homeownership, which is particularly low in Germany.

Nevertheless, the report offers a reminder that citizens in some of the countries hardest-hit by Europe's debt crisis aren't as bad off as many believe.

The question of how much taxpayer money should be put up to bail out governments in Greece, Cyprus and Portugal tops the political agenda in Germany, Europe's biggest economy and financial backer.