Research on the division of housework among same-sex partners is limited. This is because gender-cultural theories – which emphasize the significance of gender identity and motivate many studies on the topic – are implicitly assumed to be less relevant in this case. Attending to admonitions that the division of housework in same-sex households is not free from gendering processes and practices, in this study we use the high-quality data of the American Time Use Survey (ATUS; 2003-2019), to compare the association between housework and relative earnings across partnership types. Since gender-cultural theories are based on the performance of gender identity by different-sex partners, we utilize the differences between same- and different-sex partners to better understand the effect of gender-cultural determinants on the division of housework. Our comparison of the relation across partnership-types validates the power of gender-cultural mechanisms in different-sex partners, provides a better assessment of the differences in housework patterns between different types of households, and serves as a novel quantitative test of gender-cultural mechanisms in same-sex partners.