Benefits do not increase with income in a negative income tax system. I'm not sure where you got that idea from. The point of a negative income tax system is to allow total income, from the combination of work and benefits, to increase as work income increases, preventing the incentive to not work due to benefits exceeding or only matching potential work income due to a hard income cutoff for qualifying for a non-dynamic amount of benefits. In this way, as work income increases in a negative income tax system, the benefits will incrementally decrease, until the individual meets the level where they become a net payer, not receiver, but those that are net payers will not have a total income less than any of those that are net receivers.
In the system that was described it would take two units of income to decrease one unit of benefits, allowing total income to increase with an increase in levels of work income, while not having a hard cutoff for benefits. This is an approximation of what would occur in a negative income tax system and it would not result in a net decrease in earnings considering it takes twice the earnings units to lower one unit of benefits.
In the system that was described it would take two units of income to decrease one unit of benefits, allowing total income to increase with an increase in levels of work income, while not having a hard cutoff for benefits. This is an approximation of what would occur in a negative income tax system and it would not result in a net decrease in earnings considering it takes twice the earnings units to lower one unit of benefits.