RENEE MONTAGNE, HOST:
Most religions encourage some form of charity or giving. The Mormon Church is very specific about the amount they ask for. Here's Mitt Romney speaking on Fox News.
(SOUNDBITE OF FOX NEWS BROADCAST)
MITT ROMNEY: I made a commitment to my church a long, long time ago that I would give 10 percent of my income to the church. And I've followed through on that commitment.
MONTAGNE: Such dedication to giving is not unusual among Mormons. They have a very high rate of tithing, as it's called - so high, in fact, that it sparked the interest of economists. Robert Smith from NPR's Planet Money team says the Mormons teach a surprising lesson about how people relate to money.
ROBERT SMITH, BYLINE: Gordon Dahl is a Mormon. When he was growing up, he learned the simple rules of tithing.
GORDON DAHL: It's very clear that you're supposed to donate 10 percent of your income to the church. That's written in stone. Everyone knows that, and that's preached from the pulpit.
SMITH: Ah, but once Dahl became an economist - he works at UC San Diego now - he noticed something complex about tithing.
DAHL: They don't tell you what to donate 10 percent on. In other words, there is no definition of what income is. Which is really interesting to us as economists, because we want to know: How do people define income?
SMITH: It's a trickier question than you might think. Sure, your paycheck is income. But is a gift from a loved one income? What if the value of your home goes up?
The IRS has hundreds of pages of rules about these kind of things. But Professor Dahl wanted to know if people, in their hearts, had such a complicated view of money.
The Mormons were the perfect test subjects. They take tithing very seriously. And they have an incentive to be honest. After all, God is watching. So Dahl started to survey church members with hypothetical questions.
DAHL: We might ask: Suppose your parents gave you $500 for Christmas, would you pay tithing on that money?
SMITH: Most Mormons said yeah. Gifts of cash were definitely considered income. So Dahl changed it up? What about a gift of furniture?
DAHL: If your parents gave you, for example, a sofa worth $500, people wouldn't tithe the value of the gift. So, in other words, we got our first glimpse of the way people think about income is, as I'd like to say it, when they see green.
SMITH: Cash. So far, the Mormon mind isn't too different from the rules of the IRS. But the questions get trickier. We put some of the dilemmas to David Shapiro, a Mormon and a financial advisor in Littleton, Colorado.
If you find a 20 dollar bill would you kick back $2 to the Church of Jesus Christ of Latter Day Saints?
DAVID SHAPIRO: Yeah, I would.
SMITH: If you have a garage sale, would you tithe your results of the garage sale?
SHAPIRO: Umm. All of the stuff that we sold at the garage sale has already been tithed because we tithe on gross, so probably not.
MONTAGNE: It's not unusual for Mormons to have these kind of discussions. In fact, Shapiro had to have this talk with his wife when they got married. He tithes on his gross income - meaning before taxes. His wife...
SHAPIRO: She paid tithing on the net of her income.
SMITH: After taxes?
SHAPIRO: After taxes. Her logic was money that I pay to the government isn't money in my pocket, so I shouldn't have to pay tithing on that.
SMITH: Shapiro eventually convinced her to pay on the larger amount.
Gordon Dahl, the economist, says that he found that Mormons, when in doubt, tended to adopt the more simple and generous definitions of income. So, for instance in his survey, Mormons would generally say that they tithe 10 percent on the profit that they make from selling a stock.
DAHL: If you ask them a separate question and say, suppose your stock loses value, would you deduct this from your income before paying tithing? Kind of surprising to me, most people said no.
SMITH: See, when people deal with the IRS they take every deduction. When Mormons approach tithing...
DAHL: They 're worried about being petty with God. I don't want to be petty with God.
(SOUNDBITE OF LAUGHTER)
SMITH: There is a serious reason to look at all this stuff. It goes back again to the IRS. Dahl says that studies have shown that people are more willing to pay taxes if they feel that it's fair.
SHAPIRO: When people think a certain aspect of the tax code is not fair, they're more likely to try to cheat, right? And so it's important to know what people think of as fair. And when you have to define it yourself for religion, you get to decide for yourself what you think is fair.
SMITH: Of course, as Dahl found out, this deciding for yourself can get complicated. I asked a Mormon bishop in Salt Lake if a few more rules might make tithing easier on Mormons. He said all this soul-searching about what you owe God is, kind of, the point.
Robert Smith, NPR News.
(SOUNDBITE OF MUSIC)
MONTAGNE: You're listening to MORNING EDITION from NPR News.