One of the first things you learn in Means-Tested Welfare Economics 101 is that means-tested welfare programs produce enormous marginal tax rates. Say you have a $5,000 benefit that's available only to people making less than $10,000. If you have market income of $9,000, this means you have total income of $14,000. But if you have market income of $11,000 you have total income of $11,000. You're essentially paying a marginal tax rate of over 100%.