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Option 16:

Introduce Mark-to-Market Taxation of Capital Gains

Topline Estimates

Gross Domestic Product (GDP)
0.0%
Gross National Product (GNP)
-0.1%
Full-Time Equivalent Jobs
0
Wage Rate
0.0%
Capital Stock
0.0%
Conventional Primary Deficit Change (10‑Yr)
-$628.3B
Dynamic Primary Deficit Change (10‑Yr)
-$627.2B
Dynamic Total Deficit Change (10‑Yr)
-$800.5B

Source: Tax Foundation General Equilibrium Model.

Under the current tax system, investors are generally not required to pay taxes on capital gains until they sell their assets. The ability to defer taxes on capital gains reduces the effective tax rate on gains and creates a lock-in effect as investors can minimize their tax liability by holding their assets for longer periods.

This option implements mark-to-market taxation of capital gains for taxpayers with over $1 billion in assets or $100 million in income for three consecutive years, subjecting capital gains of high-income taxpayers to taxation on an annual basis. Mark-to-market would remove investors’ choice about when to pay taxes on gains, thus eliminating the lock-in effect created by the ability to defer taxes, but would lead to new problems, including administrative complexity, especially for illiquid assets, and reduced incentives to save.

On a conventional basis, this option would decrease the primary deficit by $628.3 billion over the budget window. Long-run GDP would be unchanged, while long-run GNP would fall by 0.1 percent. Incorporating changes in interest costs, the debt-to-GDP ratio would reach 172.6 percent by 2056.

The tax increase would be concentrated among taxpayers in the top 0.01 percent, who would see a decrease in after-tax income of 8.3 percent in the first year of the policy, stabilizing to a 2.2 percent decline in the long run.

Modeled Results

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About the Authors

Erica York Tax Foundation
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Erica York

Vice President of Federal Tax Policy

Erica York is Vice President of Federal Tax Policy with Tax Foundation’s Center for Federal Tax Policy. Her analysis has been featured in The Wall Street Journal, The Washington Post, Politico, and other national and international media outlets.

Garrett Watson Tax Foundation
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Garrett Watson

Director of Policy Analysis

Garrett Watson is Director of Policy Analysis at the Tax Foundation, where he conducts research on federal and state tax policy. His work has been featured in The Washington Post, The Atlantic, Politico, the Associated Press and other major outlets.

Huaqun Li Tax Foundation
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Huaqun Li

Senior Economist, Director of Modeling Projects

Dr. Huaqun Li is Senior Economist, Director of Modeling Projects at the Tax Foundation. She focuses on developing and maintaining the Foundation’s Taxes and Growth Model, which models the budgetary and economic effects of changes to federal tax policy.

William McBride or Will McBride Tax Foundation
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William McBride

Chief Economist & Stephen J. Entin Fellow in Economics

Dr. William McBride is the Chief Economist & Stephen J. Entin Fellow in Economics at the Tax Foundation, where he oversees major research projects primarily related to reforming the federal tax code, advancing sound tax policy, and improving the federal government’s fiscal outlook.

Alex Durante Tax Foundation
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Alex Durante

Senior Economist

Alex Durante is a Senior Economist at the Tax Foundation, working on federal tax policy and model development. Alex worked as a research assistant at the Federal Reserve Board and served as a staff economist on the Council of Economic Advisers.

Alex Muresianu Tax Foundation
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Alex Muresianu

Senior Policy Analyst

Alex Muresianu is a Senior Policy Analyst at the Tax Foundation, focused on federal tax policy. Previously working on the federal team as an intern in the summer of 2018 and as a research assistant in summer 2020. He attended Tufts University, graduating with a degree in economics and minors in finance and political science.

Peter Van Ness Tax Foundation

Peter Van Ness

Research Software Developer

Peter Van Ness is a Research Software Developer at the Tax Foundation working on federal tax policy and model development. Peter previously worked as a research assistant at another think tank and as a data analyst at a consulting firm.

Aleksei Shilov Tax Foundation Research Software Developer

Aleksei Shilov

Research Software Developer

Aleksei Shilov is a Research Software developer at the Tax Foundation working on economic model development and federal tax policy. Aleksei joined the Tax Foundation as an intern in January 2025. He holds a B.S. in computer science and a minor in economics from Northeastern University and is currently based in Boston, MA.

Daniel Bunn Tax Foundation President & CEO
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Daniel Bunn

President and CEO

Daniel Bunn is President and CEO of the Tax Foundation. Daniel has been with the organization since 2018 and, prior to becoming President, successfully built its Center for Global Tax Policy, expanding the Tax Foundation’s reach and impact around the world. Prior to joining the Tax Foundation, Daniel worked in the United States Senate at the Joint Economic Committee.