The math behind the calculator

A negative income tax has three parameters, and any two of them pin down the third:

G = guaranteed income (payment at $0 earnings)
t = phase-out rate
B = break-even income = G ÷ t
Payment(E) = max(0, G − t × E) = t × max(0, B − E)
Total income(E) = E + Payment(E)
Effective marginal rate = t below B, 0% above B

With the defaults — a $12,000 guarantee and a 50% rate — the break-even income is $24,000. A household earning $16,000 receives $12,000 − 0.5 × $16,000 = $4,000, for a total of $20,000. Every additional dollar it earns raises total income by 50 cents until earnings reach $24,000, where the payment ends.

Friedman described the program the other way around: start from the income level at which a family would owe no tax (in his framing, its unused exemptions and deductions), and pay back a fraction of the shortfall below that level. Both framings describe the same schedule, which is why the calculator lets you set either the guarantee or the break-even point.

Friedman's 1962 proposal

Friedman set out the negative income tax in Capitalism and Freedom (1962), in the chapter on the alleviation of poverty. His argument had three parts:

  • Help people because they are poor, not because they belong to a particular occupation, age group, or industry — which, he argued, is what most existing programs, including wage and price regulations, actually did.
  • Pay in cash, through the tax system, so recipients choose how to spend it and the administration piggybacks on machinery that already exists.
  • Replace, don't add. He presented the NIT as a substitute for a patchwork of separate welfare programs, not a layer on top of them, and was explicit that its cost should be weighed against what it replaced.

He also flagged the central design tension himself: because the payment falls as earnings rise, the program works like a tax on extra earnings over the phase-out range. A rate well below 100% preserves some reward for working; a higher guarantee or lower rate raises the cost. That trade-off is exactly what the sliders above let you explore.

Not a fringe idea Versions of the negative income tax were also developed by economists across the spectrum, including James Tobin and Robert Lampman. In 1968 more than a thousand economists signed a public statement urging Congress to adopt a system of income guarantees and supplements. President Nixon's Family Assistance Plan (proposed in 1969) borrowed the NIT structure for families with children; it passed the House but died in the Senate.

How it relates to the EITC

The Earned Income Tax Credit, enacted in 1975, is often described as the NIT's descendant. The family resemblance is real — both run through the tax code and both phase out as income rises — but the shapes differ in one decisive way:

  • An NIT pays the most at zero earnings and phases down from there. It is a floor under income whether or not anyone in the household works.
  • The EITC pays nothing at zero earnings. It phases in as earnings rise (a wage subsidy), plateaus, and only then phases out. Over the phase-in range its marginal rate is negative: each extra dollar earned brings more than a dollar of income.

That difference is deliberate. Congress chose to condition support on work, which avoids the NIT's phase-out disincentive at the very bottom but leaves households with no earnings outside the program. The EITC still has a phase-out range, and there it imposes its own implicit tax — roughly 16–21% for families with children, on top of ordinary taxes. For the side-by-side comparison with wage floors, see Minimum wage vs. EITC.

The 1968–1982 income-maintenance experiments

Before adopting anything like an NIT nationally, the federal government did something unusual: it ran randomized field experiments. Between 1968 and 1982, four experiments assigned families to different combinations of guarantee and phase-out rate and compared them with control groups:

  • New Jersey (and Pennsylvania) Income Maintenance Experiment — the first, focused on urban two-parent families, beginning in 1968.
  • Rural Income Maintenance Experiment — rural families in Iowa and North Carolina.
  • Gary, Indiana experiment — focused largely on Black families, including single-parent households.
  • Seattle–Denver Income Maintenance Experiment (SIME/DIME) — the largest and longest, running into the early 1980s.

The findings most often summarized from these studies are cautious ones:

  • Work effort fell, but did not collapse. Recipients reduced hours worked relative to the control groups. The reductions were comparatively modest for primary earners and larger for second earners (often wives) and young people.
  • Size depended on design. More generous guarantees and higher phase-out rates were generally associated with larger work reductions — consistent with basic labor-supply theory.
  • Some results were contested. Early SIME/DIME analyses reported higher rates of marital dissolution among some treatment groups, a finding that weighed on the policy debate; later reanalyses disputed it.
  • Interpretation is tricky. The experiments were temporary, which may change how people respond compared with a permanent program, and income reporting by participants raised measurement issues.

The experiments are widely regarded as a methodological milestone in social science. Politically, they arrived just as the large-scale NIT proposals of the era stalled, and the evidence that work did respond to the program's parameters became part of the case for the work-conditioned EITC instead.

The work-incentive debate

The calculator makes the core problem visible. Because B = G ÷ t, there is an unavoidable three-way trade-off, sometimes called the "iron triangle" of income support:

Adequate guaranteeA higher G means more support for households with little or no earnings.
Strong work incentiveA lower t means each extra dollar earned is taxed less.
Contained costA lower B means fewer households qualify and the budget stays smaller.

Pick any two and the third moves against you. Try it: hold the guarantee at $12,000 and drop the rate from 50% to 25%, and the break-even income doubles from $24,000 to $48,000 — the program now reaches well into the middle of the income distribution. Raise the rate to 100% instead, and the break-even falls to $12,000, but total income stays flat at the guarantee until earnings exceed it. Working more pays nothing at all over that range.

Supporters of the NIT argue that this trade-off is honest and visible, whereas the patchwork of programs it would replace often stacks several phase-outs on top of one another, producing combined implicit rates that are higher and harder to see. Critics respond that any guarantee paid regardless of work will reduce work at the margin, and that the experiments confirmed it. Both points can be true; the design question is how much reduction is an acceptable price for a given level of support.

Why this belongs on a minimum-wage site

Friedman's objection to the minimum wage was that it tries to fight poverty by outlawing low-paid jobs, which helps the workers who keep their jobs at the higher wage and does nothing — or harm — for those who don't. The comparison lines in the chart capture that logic in its simplest form: under a minimum-wage-only policy, a worker whose market wage is below the floor ends up either on the "job kept" line or the "job lost" line, and no transfer catches them in between. Under an NIT, income rises continuously with earnings and never drops to zero.

How many workers land on each line in reality is the contested empirical question — see what Friedman actually argued and the research tracker. And as with the EITC, some economists argue a moderate wage floor and a transfer can complement each other rather than compete.

Further reading