Most welfare systems don't have a cliff where you lose more than you earn; they phase out. For example, in the US, the child tax credit is reduced by $50 for ev

Most welfare systems don't have a cliff where you lose more than you earn; they phase out. For example, in the US, the child tax credit is reduced by $50 for every $1,000 earned above a threshold, so the phaseout is a 5% "tax" on income in that range rather than being a welfare cliff. A phase-out reduces effective hourly wage, which theoretically reduces the incentive to work. That's no different than any other kind of marginal tax rate, though, and UBI would require a high marginal tax rate. Probably the best argument UBI is to replace current welfare systems with one cash payment because, in addition to theoretically reducing administrative costs, it would make phase-outs easier to understand. If there are welfare recipients who misunderstand when benefits apply, they might not want to obtain additional income even though it would benefit them.