Common Cents: Bank Account Structure and Couples’ Relationship Dynamics

When a romantic relationship becomes serious, partners often confront a foundational decision about how to organize their personal finances: pool money together or keep things separate? In a six-wave longitudinal experiment, we investigated whether randomly assigning engaged or newlywed couples to merge their money in a joint bank account increases relationship quality over time. Whereas couples assigned to keep their money in separate accounts or to a no-intervention condition exhibited the normative decline in relationship quality across the first two years of marriage, couples assigned to merge money in a joint account sustained strong relationship quality throughout. The effect of bank account structure on relationship quality is multiply determined. We examine—and find support for—three potential mechanisms using both experimental and correlational methods: merging finances 1) improves how partners feel about how they handle money, 2) promotes financial goal alignment, and 3) sustains communal norm adherence (e.g., responding to each other’s needs without expectations of reciprocity). While prior research has documented a correlation between financial interdependence and relationship quality, our research offers the first experimental evidence that increasing financial interdependence helps newlyweds preserve stronger relationship quality throughout the newlywed period and potentially beyond.