Elon Musk’s effective federal tax rate has swung from zero in some years to near the top statutory rate in others. ProPublica’s analysis of leaked IRS records put his “true tax rate” at roughly 3.27% between 2014 and 2018, measured against the growth in his net worth, with about $455 million in federal income taxes paid over that span. In 2018 his federal income tax bill was zero. In 2021, exercising a large block of Tesla stock options triggered a payment he described as roughly $11 billion. Those numbers are not contradictions. They are what happens when a fortune sits almost entirely in company stock and the tax code only taxes transactions.
What an Effective Tax Rate Measures
An effective tax rate is total federal income tax paid divided by total income. It almost always comes in below the top statutory bracket of 37%, because income is taxed in layers and only the slice above $626,351 for a single filer hits the top rate.1Internal Revenue Service. Federal Income Tax Rates and Brackets
The controversy around Musk’s rate is not really about the numerator. It’s about what belongs in the denominator. For a salaried worker, “income” is what shows up on the W-2. For someone whose wealth is concentrated in appreciating stock, the IRS definition of income and the amount by which someone got richer in a given year are different numbers, sometimes by orders of magnitude. Pick the legal definition and Musk’s rate looks normal in years he had transactions. Pick wealth growth and it looks tiny.
Why Unrealized Gains Produce Zero-Tax Years
Federal tax law taxes gains only when you sell. The technical term is realization. Section 1001 of the Internal Revenue Code defines gain as the excess of the amount realized from a sale or disposition of property over the adjusted basis.2Office of the Law Revision Counsel. 26 US Code 1001 – Determination of Amount of and Recognition of Gain or Loss Until a sale happens, appreciation is unrealized and owes nothing.
Section 61’s definition of gross income includes “gains derived from dealings in property,” but holding stock as it rises in value is not a dealing.3Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined If shares you own climb from $1 billion to $50 billion in value, your net worth rose by $49 billion and your taxable income from that stock is zero. The IRS treats income as taxable when you actually receive it.4Internal Revenue Service. Taxable Income
That’s how Musk’s 2018 federal income tax bill was zero. If you don’t sell, don’t exercise options, and don’t have significant ordinary income, there is nothing for the IRS to tax, and any losses from other ventures can offset whatever taxable income does exist.
The 2014–2018 Numbers
ProPublica’s 2021 investigation obtained years of confidential IRS records for the wealthiest Americans and coined the “true tax rate,” comparing taxes paid to the growth in Forbes-estimated net worth. Across the 25 richest people, that rate was 3.4% over 2014–2018. Musk’s individual figure was 3.27%, reflecting about $455 million in federal income taxes on roughly $14 billion in wealth growth.
The metric was controversial precisely because it measured against wealth rather than legally defined income. Critics called it apples to oranges. Defenders said that when net worth rises by billions and the tax bill is zero, the legal definition of income is the problem. Both positions describe the same underlying fact: US tax law was not built to reach paper wealth, and someone whose fortune lives in unsold shares can go years without a large tax event.
The 2021 Option Exercise
The other side of years of deferral is that when a realization event finally hits, the bill is enormous. In 2021, Musk exercised a tranche of Tesla stock options granted in 2012 as CEO compensation. Those options were approaching expiration, so exercising was not really optional if he wanted the value.
Section 83 of the Internal Revenue Code taxes property received in connection with services as ordinary income, based on the spread between what the employee paid and what the property is worth.5Office of the Law Revision Counsel. 26 US Code 83 – Property Transferred in Connection With Performance of Services Musk’s strike price was roughly $6.24 per share against a much higher market price, producing about $23.5 billion in ordinary income. At the 37% top rate plus the 3.8% Net Investment Income Tax, the option exercise alone generated roughly $10.7 billion in federal tax. Additional capital gains from separate share sales brought the total to an estimated $11 billion, which Musk publicly called the largest individual federal income tax payment in history.
His effective rate on the option exercise itself was close to the top statutory rate. Option compensation is ordinary income, with none of the preferential treatment given to long-held capital gains.
Buy, Borrow, Die: Why the Ongoing Rate Stays Low
The realization rule explains zero-tax years. But it raises an obvious question: how does someone fund a lifestyle without selling? The standard answer for holders of highly appreciated stock is a strategy often called buy, borrow, die.
Rather than sell shares and trigger capital gains tax of up to 20% plus the 3.8% NIIT surtax,6Internal Revenue Service. Topic No. 409, Capital Gains and Losses wealthy individuals borrow against their holdings. Banks will lend a substantial percentage of a stock portfolio at low rates because the collateral is liquid. Loan proceeds are not income, because the borrower also owes the bank, so there is no net gain to tax.7Internal Revenue Service. For Senior Taxpayers Interest on loans used for investment purposes may even be partially deductible, subject to the net investment income limit.8Office of the Law Revision Counsel. 26 US Code 163 – Interest
The die part comes from Section 1014. When someone dies, heirs receive assets with a cost basis reset to current market value. Unrealized gains accumulated during the owner’s lifetime are erased for income tax purposes. If shares bought at $10 are worth $1,000 at death, the heirs inherit them with a $1,000 basis and could sell the next day owing no capital gains tax. The estate can use share sales to repay outstanding loans, and the deferred capital gains tax on a lifetime of appreciation is never collected.
None of the three pieces is a loophole in the sense of an accidental gap. The realization requirement, the treatment of loan proceeds, and the stepped-up basis at death are deliberate features of the code. Combined, they let holders of appreciated assets keep their reported taxable income small for long stretches.
Capital Gains Rates and the Texas Move
When a wealthy investor does sell, the tax rate on long-term gains is lower than the rate on wages. Assets held more than a year are taxed at a federal maximum of 20%.6Internal Revenue Service. Topic No. 409, Capital Gains and Losses The 3.8% NIIT applies above modified AGI of $200,000 for singles and $250,000 for joint filers, bringing the combined top federal rate on investment gains to 23.8%. Those NIIT thresholds have not been adjusted for inflation since the tax was created in 2013.
Compare that with wages: a salaried employee at $700,000 pays 37% federal on the top slice, while an investor realizing $700,000 in long-term capital gains pays a maximum of 23.8%.1Internal Revenue Service. Federal Income Tax Rates and Brackets The differential is a deliberate policy choice, and it is a major reason effective rates for the very wealthy tend to run below those for high-earning professionals living on salary.
State tax adds a separate layer, from 0% in states with no income tax to over 13% in the highest. Musk relocated from California to Texas, which has no state income tax, a move that on future stock sales or option exercises can represent billions in savings on its own.
Charitable Giving as a Rate Reducer
Donating appreciated stock instead of cash accomplishes two tax outcomes at once. The donor can deduct the full fair market value of the shares and never pays capital gains tax on the built-in appreciation. Cash donations to qualifying public charities are deductible up to 60% of adjusted gross income; appreciated property donated to private foundations is capped at 30% of AGI, with a five-year carryforward for excess.
Starting in 2026, charitable deductions only count for the portion exceeding 0.5% of AGI. The 60% cash limit for public charities has been made permanent. For a billionaire donor, giving stock rather than writing a check produces significantly better tax math, which is why large gifts from the ultra-wealthy are typically funded with shares.
What 2026 Changes and What Does Not
Many individual provisions of the 2017 Tax Cuts and Jobs Act were set to expire at the end of 2025. Congress extended much of that framework through the One Big Beautiful Bill, keeping the top rate at 37% and preserving key features of the earlier structure.
For the billionaire tax debate, the important point is what did not change. There is still no federal tax on unrealized gains. Proposals for a Billionaire Minimum Income Tax have circulated in Congress, and California has floated a one-time 5% wealth tax on its roughly 200 billionaire residents, but no federal unrealized gains tax has been enacted. The step-up in basis at death also survived multiple legislative attempts to eliminate or cap it. The mechanics that let Musk’s effective tax rate swing from zero to billions in a single tax year remain in place, and the long-term planning path built around buy, borrow, die remains the most powerful tool available to holders of highly appreciated assets.