Pooling all incomes was long seen as the norm in male-breadwinner marriages, but in a time of dual-earner families, cohabitation, and divorce, the underpinnings of this model are eroding. What consequences does this have for income pooling? We compare ca. 130,000 married and cohabiting couples from 29 European countries in the 2010 European Union Survey of Income and Living Conditions (EU-SILC) via random effects logit models. We show that cohabiting couples are generally more likely than married couples to keep at least some income separately, the so-called cohabitation gap. Roughly a fifth of this gap we can attribute to compositional differences between married and cohabiting couples. Further, the cohabiting group is heterogeneous and smaller when comparing only couples with children or only couples with a long relationship duration. Lastly, we show that there is substantial variation in the size of the cohabitation gap across countries. The size of this gap varies with the country-specific cohabitation rate, divorce rate, and female labor force participation rate. While there is considerable heterogeneity among cohabiting couples, married and cohabiting couples remain distinct in their resource-sharing behavior. Income pooling does not become more comparable when cohabitation, marital instability, and women’s economic independence become more widespread in the broader society. Our study reconciles disparate findings of previous cross-national research on the cohabitation gap.