The share of women who earn more than their husbands, while still relatively small, is growing. When women do earn more, both husbands and wives seem uncomfortable — to the point of lying about it.

That’s the finding of a new paper from the Census Bureau, which compared what respondents told census surveyors about their earnings with what their employers told the Internal Revenue Service in tax filings.

In opposite-sex marriages in which women earned more, women said, on average, that they earned 1.5 percentage points less than they actually did. Their husbands said they earned 2.9 percentage points more than they did.

The census researchers, Marta Murray-Close and Misty L. Heggeness, concluded that people thought it was more socially desirable for men to earn more — so whether fudging the numbers was a conscious or unconscious choice, these social norms affected their answers. They called it “manning up and womaning down.”