This paper examines fiscal reform options in the United States with an intertemporal computable general equilibrium model of the world economy called G-Cubed. Six policy scenarios explore two overarching issues: (1) the effects of a carbon tax under alternative assumptions about the use of the resulting revenue, and (2) the effects of alternative measures that could be used to reduce the budget deficit. We examine a simple excise tax on the carbon content of fossil fuels in the U.S. energy sector starting immediately at $15 per metric ton of carbon dioxide (CO2) and rising at 4 percent above inflation each year through 2050. We investigate policies that allow the revenue from the illustrative carbon tax to reduce the long run federal budget deficit or the marginal tax rates on labor and capital income. We also compare the carbon tax to other means of reducing the deficit by the same amount.
We find that the carbon tax will raise considerable revenue: $80 billion at the outset, rising to $170 billion in 2030 and $310 billion by 2050. It also significantly reduces U.S. CO2 emissions by an amount that is largely independent of the use of the revenue. By 2050, annual CO2 emissions fall by 2.5 billion metric tons (BMT), or 34 percent, relative to baseline, and cumulative emissions fall by 40 BMT through 2050.
The use of the revenue affects both broad economic impacts and the composition of GDP across consumption, investment and net exports. In most scenarios, the carbon tax lowers GDP slightly, reduces investment and exports, and increases imports. The effect on consumption varies across policies and can be positive if households receive the revenue as a lump sum transfer. Using the revenue for a capital tax cut, however, is significantly different than the other policies. In that case, investment booms, employment rises, consumption declines slightly, imports increase, and overall GDP rises significantly relative to baseline through about 2040. Thus, a tax reform that uses a carbon tax to reduce capital taxes would achieve two goals: reducing CO2 emissions significantly and expanding short-run employment and the economy.
We examine three ways to reduce the deficit by an equal amount. We find that raising marginal tax rates on labor income has advantages over raising tax rates on capital income or establishing a carbon tax. A labor tax increase leaves GDP close to its baseline, reduces consumption very slightly and expands net exports slightly. Investment remains essentially unchanged. In contrast, a capital tax increase causes a significant and persistent drop in investment and much larger reductions in GDP. A carbon tax falls between the two: it lowers GDP more than a labor tax increase because it reduces investment. However, its effects on investment and GDP are more moderate than the capital tax increase, and it also significantly reduces CO2 emissions. A carbon tax thus offers a way to help reduce the deficit and improve the environment, and do so with minimal disturbance to overall economic activity.