# Laffer Curve **The model:** A graph showing the relationship between tax rates and tax revenues. At a 0% tax rate, revenues are zero (nothing being taxed). At a 100% tax rate, revenues are also zero (no incentive to engage in the taxed activity). Somewhere between, revenues are maximized. The curve is hump-shaped: as rates rise from 0%, revenues rise; past the revenue-maximizing rate, further rate increases reduce revenues because the discouragement of the taxed activity outpaces the increased rate. The mathematical relationship is uncontroversial. The empirical question is *where* on the curve current rates sit, which determines whether a rate cut would raise or lower revenue. The Laffer Curve became politically explosive in the 1970s-80s when its proponents claimed U.S. rates were on the right side of the hump (so cutting rates would raise revenue). The empirical record of subsequent decades indicates the rates were on the left side (cuts reduced revenue) — a finding consistent with most of the mainstream economic literature. ## The Mechanism **Behavioral response is the mechanism.** Higher rates reduce the *amount of taxed activity* through standard supply-and-demand effects (people work less, invest less, report less income to authorities, move activity offshore). The strength of the behavioral response is measured by Elasticity — how much taxed activity changes per unit rate change. **Where the peak sits depends on elasticity.** High-elasticity activities (where small rate changes produce big behavioral responses) reach the revenue-maximizing peak at low rates. Low-elasticity activities (small responses to rate changes) keep producing revenue at high rates. So the Laffer Curve isn't a single curve — it's a different curve for each tax base. **Empirical estimates of the peak vary widely.** For top marginal income tax rates, mainstream estimates of the revenue-maximizing rate range from 50% to 70% depending on assumptions about behavioral response. Current U.S. top marginal rates (37% federal + state) are well below most credible estimates of the peak — meaning rate increases would, by the Laffer-curve framework, raise revenue rather than reduce it. The Laffer-curve case for further rate cuts is therefore empirically weak in the U.S. context. **The argument is often made qualitatively when it can't be made quantitatively.** Laffer-curve rhetoric frequently invokes the curve's existence (true) without specifying where current rates sit (the actual question). "Tax cuts pay for themselves" is a strong empirical claim that requires showing rates are above the peak; the empirical record consistently shows they are not. ## KB Applications ### The 1981 [[Reagan Tax Cuts]] and the Stockman Confession The 1981 Reagan tax cuts were the canonical Laffer-curve test. Proponents claimed the cuts would pay for themselves through increased growth. The empirical record: revenues fell, deficits exploded, and the 1982 and 1986 tax increases were designed to recover lost revenue. [[David Stockman]], Reagan's OMB director, [told William Greider in 1981](https://www.theatlantic.com/magazine/archive/1981/12/the-education-of-david-stockman/305760/) that the supply-side argument was political cover for what was actually a transfer to high-income taxpayers — the Laffer-curve claim was understood internally to be unsupported. ### The [[Bush Tax Cuts]] and the Trump Tax Cuts (2001, 2003, 2017) Each subsequent major U.S. tax cut has been justified partly by Laffer-curve arguments, and each has produced revenue declines roughly matching standard (non-Laffer-curve) projections. The 2017 Tax Cuts and Jobs Act had the most explicit dynamic-scoring effort, with the Trump administration projecting GDP growth that would offset most of the revenue loss. The actual GDP growth was unremarkable; revenue did decline approximately as standard models predicted. The Laffer-curve case has now been empirically tested four times (1981, 2001, 2003, 2017) and has produced wrong predictions every time. ### The Kansas Experiment (2012-2017) The most explicit U.S. Laffer-curve test was Kansas Governor Sam Brownback's 2012 tax cut, billed as a "real-time experiment" in supply-side economics. Brownback eliminated taxes on pass-through income and dramatically cut individual rates. The result was severe budget deficits, education and infrastructure cuts, no compensating growth, and bipartisan repeal of the cuts in 2017. The Kansas experiment is now treated by mainstream economists as a definitive empirical refutation of strong Laffer-curve claims at U.S. marginal rates. ### Why the Argument Survives the Empirical Refutation The Laffer-curve argument continues to be made despite consistent empirical failure because: 1. The mathematical existence of the curve is correct (so opponents can't refute the framework, only the application) 2. The political coalition advocating tax cuts has interest in the argument regardless of evidence 3. Counter-evidence is always reframable ("growth would have been even slower without the cuts") 4. The constituency benefiting from cuts is concentrated; the constituency paying for them via deficits or other taxes is dispersed The pattern is consistent with how empirically-weak claims survive in politically-motivated rhetoric: the claim's structural utility outlasts its empirical support. ### The Honest Form of the Argument A defensible Laffer-curve case can still be made for *very high* tax rates — 90%+ marginal rates almost certainly do produce behavioral response sufficient to reduce revenue. Some European cases of wealth-tax reductions have produced revenue increases (because wealth taxes are on highly mobile assets). The honest version of the argument is narrow and applies to specific high-rate or high-mobility tax bases. The political deployment of the argument has consistently overstated its applicability. ## See Also - [[Supply and Demand]] — the market-clearing logic underneath the Laffer curve - Elasticity — what determines where the curve peaks - [[Supply-Side Economics]] — the broader school of thought - [[Trickle-Down Economics]] — the political ideology that operationalized Laffer-curve claims - [[Art Laffer]] — the namesake economist - [[Dynamic Scoring]] — incorporating macroeconomic feedback into budget estimates, and how a modeling choice relocated a political fight into an assumption - [[Mathematics and Power Hub]] — where quantification meets politics: redistricting optimization, scoring rules, risk models, algorithmic decision systems, and quantitative pseudo-proof - [[The Laffer Curve as Existence Proof]] — a mathematical critique of the Laffer argument — why proving a maximum exists says nothing about where it is