The thing that discourages work is (mostly) not the cash grant itself, but the high effective marginal tax rate you get from phasing it out as the recipient ear

The thing that discourages work is (mostly) not the cash grant itself, but the high effective marginal tax rate you get from phasing it out as the recipient earns more. The negative income tax and the earned income tax credit (which is almost the same thing) should actually encourage work among those with low incomes, because the more you earn, the larger the credit.