Form 8960

Form 8960 calculates the net investment income tax — a 3.8% Medicare surtax on certain unearned income for individuals, trusts, and estates above specified thresholds. Enacted under the Affordable Care Act, this tax applies to investment gains, dividends, interest, and passive business income, creating a separate layer of federal taxation on top of ordinary income tax.

Who must file Form 8960

The form is required if you exceed the income thresholds — $200,000 for single filers, $250,000 for married filing jointly, and $125,000 for married filing separately — AND you have net investment income. The threshold applies to modified adjusted gross income (MAGI), which is generally your regular AGI, making the calculation straightforward for most taxpayers.

Not every investor needs this form. If your income sits below the threshold, you owe no Medicare surtax. If you live in a state with very high earners, however, it’s worth understanding the mechanics: the tax catches not just the wealthy, but also retirees with substantial portfolio income or professionals with passive business interests.

What counts as net investment income

The taxable base includes interest, qualified and ordinary dividends, capital gains — both short and long-term — net rental income, and passive activity gains. Most forms of unearned income land here, with a few exceptions: tax-exempt interest does not; Medicare premiums and self-employment income do not; and certain distributions from retirement accounts are carved out.

The net investment income is the difference between investment income and investment expenses (brokerage fees, investment advisory costs). Importantly, you cannot deduct ordinary income tax items like the standard deduction. This separation ensures the tax applies only to the true economic gain.

The threshold and modified adjusted gross income

The three thresholds — $200,000, $250,000, and $125,000 — remain fixed; they have not been adjusted for inflation since the tax’s inception in 2013. For high-income earners, this means the tax is slowly catching more and more people as nominal incomes rise, even if real purchasing power stays flat. An investor with $220,000 of ordinary income and $15,000 of dividend income pays the surtax on the dividends because combined MAGI exceeds $200,000.

MAGI for this calculation is usually your AGI plus certain add-backs like foreign earned income and tax-exempt interest. The IRS instructions to Form 8960 detail these add-backs precisely. Most taxpayers find that their MAGI equals their AGI.

Calculating the tax

The actual tax owed is the lesser of (1) net investment income times 3.8%, or (2) the excess of MAGI over the threshold, times 3.8%. This structure prevents the tax from exceeding the value of the actual investment income. A single filer with $220,000 MAGI and $30,000 net investment income pays 3.8% on $20,000 (the excess of MAGI over the $200,000 threshold), not on the full $30,000 investment income.

Form 8960 walks through this calculation step by step, asking for income sources, expenses, and allocations. Most filers do not fill it out themselves; a tax professional typically handles it alongside the main return.

Coordination with other taxes

The Medicare surtax exists alongside the regular marginal tax rate on income. A household subject to both the surtax and the top ordinary income brackets faces an effective federal rate of 43.8% on investment income — the top 37% bracket plus the 3.8% surtax. State income tax may add further, pushing combined rates above 50% in high-tax states.

For active traders, there is nuance: if you materially participate in a trade or business, passive activity rules may exclude certain income from Form 8960. A real estate professional who actively manages rental properties might avoid the surtax on those gains.

Planning and timing

Because the Medicare surtax is permanent, high-income households often structure income and deductions to minimize it. Realizing losses in down markets can offset gains. Charitable contributions might provide deductions that reduce net investment income. Some investors use trusts or donation strategies to shift income.

However, aggressive planning carries risk. The IRS scrutinizes returns above certain income levels, and Form 8960 is often part of that examination. Legitimate strategies — like tax-loss harvesting — stand up to audit; artificial schemes do not.

See also