One Key to a Happy Marriage? A Joint Bank Account.

But among the most important discussions newlyweds can have is whether and how to merge their finances. It can be a fraught conversation, as research shows that money is a leading cause of arguments between partners.

New research from Kellogg School professor Eli Finkel shows one way couples can help preserve their relationship during those critical first years of marriage: by going all in on a joint bank account, with no separate accounts.

Joint bank accounts are already fairly common, with a slight majority of male–female couples in Western nations reporting using only joint bank accounts (52–65 percent). Still, 10–15 percent report maintaining completely separate accounts, while the rest use a combination of joint and separate accounts.

The study, which was led by Jenny Olson of Indiana University and is forthcoming in the Journal of Consumer Research, is the first longitudinal experiment to show how the way couples structure their bank account influences the quality of their relationship over time. Finkel, Scott Rick of the University of Michigan, and Deborah Small of Yale University also collaborated on the research.

The researchers determined that a joint bank account can help couples align their financial goals and adhere to communal norms, rather than behave in a more transactional way. If all money is everyone’s money, then partners don’t need to keep score.

“Understanding how bank-account structure affects marriages has been one of the major understudied topics,” Finkel says. “The newlywed years are considered the ‘connubial crucible.’ That means the dynamics that couples develop in those years predict how their relationship will progress thereafter. We wanted to take that crucial period and see if we could use bank account structure to alter how satisfied couples are in their relationships. And we found that we could.”

A way to navigate the “connubial crucible”

The first years of a marriage are key to its success. Research shows relationship quality peaks around the wedding day and then begins a long decline that can be especially steep in the early years.

The research team sought to counter that decline. Previous studies have shown a link between holding a joint bank account and having a higher quality relationship. Perhaps couples with a shared account might prompt each other to consider how their purchase will affect their partners or might facilitate transparency around finances.

But those previous studies only showed correlation, not causation. To study whether joint or separate bank accounts can directly affect relationship quality over time, the research team recruited 230 male–female couples who were engaged or recently married and who currently maintained separate bank accounts for each partner.

They then randomly assigned couples to one of three bank-account-structure conditions. Some couples were instructed to merge their accounts into one joint account. Others were instructed to keep their accounts separate. And a third group was told they could create or maintain whatever account structure they wanted.

The research team then followed these couples across the connubial crucible, surveying the partners separately every three months during the first year and then again at the end of the two years. To understand the quality of the couple’s relationship, the researchers measured the couple’s satisfaction, conflict tactics (how often they shouted at their partner, for example), and how well the couple interacted. To better understand the couple’s financial harmony, the research team had each partner indicate how much they agreed with such statements as “My partner is satisfied with my attitudes toward money.” The team then analyzed couples’ combined answers to determine their relationship quality and financial harmony over time.

How bank-account structures affect new marriage dynamics

At the beginning of the experiment, couples in all three groups had similar levels of relationship quality.

But when the research team analyzed the couples’ answers over two years, they found stark differences depending on how they structured their bank accounts. Couples assigned to maintain completely separate and those left to their own devices showed significant declines in relationship quality over time. (Of the couples in this no-intervention group, 72 percent kept separate accounts throughout the period.)

But couples who had merged all their money into a joint account did not exhibit those same declines. They maintained the quality of their relationship and also showed greater financial harmony than the other couples.

“The effect was even bigger than I anticipated,” Finkel says. “Most every study shows that satisfaction declines after the wedding day. We were delighted that we were able to take a sample of newlyweds and show not only did their marital quality not decline, it might have even increased slightly. And we didn’t train them on how to connect better or have better communication skills. The account structure itself was sufficient to keep people happier throughout the newlywed period.”

Helping newlyweds adhere to communal norms

To better understand why the joint accounts were so helpful for preserving relationship quality, the research team ran another study that recruited 507 married individuals who had been married an average of 15 years. The participants answered questions about their banking (whether they had merged accounts), financial harmony with their spouse (such as “Are you happy with the amount of money that you and your partner together are routinely spending?”), and whether spouses ought to keep track of benefits given and received to keep them in balance.

The researchers found that people who had merged bank accounts with their partner experienced a deeper sense of aligned financial goals and stronger communal norm adherence. Previous research by Finkel shows that couples who adopt stronger communal norms tend to be happier in their marriages.

Joint accounts are not for everyone

While the evidence suggested that encouraging participants to get joint bank accounts can improve marital satisfaction, several questions remain.

The research team found that partially merging accounts (creating a joint account while still maintaining separate counts) was not associated with the same benefits as going all in. However, Finkel hesitates to draw major conclusions from that finding and instead suggests a need for future research to dig in further.

And while joint accounts benefited the participants of the study on average, such benefits might not accrue to everyone. A joint account requires partners to give up a certain measure of independence. Those who are in fraught circumstances might find their finances being controlled or find themselves at risk for abusive behavior.

“We also need to consider situations where people are starting off more precarious in their relationship or finances,” he says. “Would a joint account have the same effect? Would it be worth the risk for couples to go all in? This research has opened up an array of additional questions that now need to be explored.”