Why do married people pay most of the taxes in the US?

The share of American adults who are married is slipping, but married couples still pay the lion’s share of income tax, according to a new analysis by the Pew Research Center.

The finding may even reflect issues like differences in who chooses marriage and who doesn’t and the financial benefits of those choices.

The Pew report said the proportion of adults who are married has dropped steadily over 40 years, but married adults — including both those who file as “married, filing jointly” and as “married, filing separately” — paid 74 percent of income taxes in 2014, when half of American adults were married.

The numbers reflect a growing gap. In 1970, the report said, 69 percent of adults were married and they paid 80 percent of income taxes.

Married couples were responsible for 38 percent of the tax returns filed, the report found.

“The fact that married Americans continue to pay roughly three-quarters of the nation’s income taxes, in spite of their dwindling share of the adult population, is in part a result of the changing demographics and economics of marriage,” wrote the report’s author, Anthony Cilluffo.

“Marriage is increasingly linked with higher levels of education, which are in turn linked to higher incomes.”

Marriage has been losing ground for years among those with lower levels of education, while those with college degrees are much more likely to marry. Forty-five percent of high school grads with no college are married, compared to 62 percent of college grads in 2015.

Theories about what underpins the numbers vary, depending on who is asked. But experts suggest couples who choose marriage may share traits or behaviors associated with more economic success.

“These findings confirm the growing gap between married and unmarried couples and families. Those with more resources and education are those most likely to marry. They feel more confident about marriage and they have more resources to reduce stressors that make marriage harder,” said Scott Stanley, research professor, co-director of the Center for Marital and Family Studies at the University of Denver and senior fellow for the National Marriage Project and the Institute for Family Studies.

At the same time, “marriage is associated with higher levels of commitment to a future together, and higher commitment will reinforce behavior consistent with an ‘us with a future’ approach to life. That makes it more likely two people will combine and manage resources together — and be accountable to each other for how things are handled — compared to relationships (married or not) where there is less of a clear sense of building something for the future as a team,” said Stanley, who wrote “The Power of Commitment: A Guide to Active, Lifelong Love.”

Stephanie Coontz, director of research and public education for the Council on Contemporary Families, believes the finding that married couples, while fewer in number, pay a larger portion of income tax primarily reflects the fact that with folks marrying at older ages, “your single population contains a lot more people who are younger and in the early stages of their job histories and who therefore have lower earnings and may owe very little or may actually get refunds because they are in school or in such low-wage occupations that whatever jobs they held actually withheld more taxes than they ended up owing.”

Married couples tend to be wealthier, “not so much because they are married as because, far more than in the past, having a college degree and strong earnings power is a really important factor that predicts marriage,” said Coontz, who teaches at The Evergreen State College in Olympia, Washington. She has written several books on marriage and family, including “The Way We Never Were: American Families and the Nostalgia Trap.”

Coontz said those who have both more work experience and more earning power are “over-represented” among married couples. And most marriages now contain two wage earners.

“To the extent their finances depend on income instead of stock market wealth, real estate dealings and other activities that get people big tax breaks, they don’t get the same tax breaks that wealthy single people do — or wealthy male-breadwinner families,” she said.

“People talk about the singles tax penalty, but it was actually put in after WWII as a male-breadwinner tax bonus, allowing a couple with one high earner and one non-earner to average out their incomes and pay a lower rate than individuals or couples whose taxes were reckoned on their own incomes.”

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