By Jana Riess, with research by Benjamin Knoll

Tis the season for tithing settlement. Among Mormons, December is a month in which we are invited to voluntarily sit down with the bishop and declare ourselves full or partial tithe payers.

In my research for The Next Mormons—based on a survey that analyzes the beliefs, attitudes, and practices of four generations of current and former Latter-day Saints in the United States—one of the questions we asked was about tithing practices.* Who tithes, and how much? Do most Mormons pay tithing off of gross or net income?

I was particularly interested to see whether there would be generational differences among full tithe-payers, or those who give 10% of their income. To obtain a Mormon temple recommend, a church member merely has to declare himself or herself as “a full tithe-payer,” but the specific details of that (gross or net?) are questions that bishops are not permitted to ask.

I am not a bishop but a nosy historian, so I asked.

On the surface, there’s not much generational difference among those self-identified Mormons who declare themselves to be full tithe-payers.

Here’s how it breaks down by age cohort in those who say that they “regularly give 10%” of their before-tax or after-tax income “to the LDS Church.”

Overall, these are extraordinarily high numbers for generosity—and the youngest Mormons are edging out their elders. While the statistical difference is tiny and within the margin of error, it looks like the under-35 Mormons have the highest rates of tithing of any generation, and GenX the lowest. (Maybe there’s a legit reason why our elders called our generation “slackers.” We’re really sorry.)

But when we look a little deeper at the data, some more significant generational differences emerge. Here are graphs showing the percentage of people who pay tithing by gross and net income:

Here you can see that the practice of tithing on gross income has slipped from one generation to the next, with the largest change coming between the Boomers and GenX. (Sorry again.)

So while it looks like Mormon Millennials are just as likely (if not slightly more!) to pay 10% of their income as tithing, they also appear to interpret “income” less rigidly than older members.

To Read:

* The fine print: The entire survey garnered 1696 complete responses, including both the “current” and the “former” samples. For this question on tithing, 1155 people who self-identified as current Mormons responded. (This only includes current Mormons, not those who have left the Church; the more than 500 former Mormons who participated in our survey were not asked this particular question.)

The Baby Boomers (born from 1945-1964) are combined with the Silent Generation (born from 1928 to 1944) because we did not have enough members of the Silent Generation to be able to make reliable conclusions from that generation by itself. The margin of error would be too high.

But if you’re interested, 62% of our Silent Generation members said they pay tithing from gross income, and only 11% pay from their after-tax income. That means the SGs have the highest rate of tithing overall (73%) and are more than 20 points higher than Millennials and GenXers in the percentage who tithe from their before-tax income.

For simplicity, percentages have been rounded up or down so that 68.3% becomes 68% and 69.6% becomes 70%. As a result, the tallies when any two numbers are added together (e.g., gross tithers + net tithers = all tithers) will be within one percentage point of the correct total but may not be exact.