[todd8]

From the US Congressional Budget Office[1]:

"When workers’ earnings rise but their after-tax income rises less—because of increases in their income and payroll taxes or declines in their benefits from government programs—their incentive to work typically declines"

[1] https://www.cbo.gov/publication/52472

[yourbandsucks]

That's only really relevant when people cross some thresholds at the very bottom of the income scale that cause them to lose benefits, though.

Otherwise, it's just trivially true for any taxation regime: a flat 1% tax means your after-tax income rises less than your pre-tax income.