How LLC Owners Save on Taxes in 2026

FREE DOWNLOAD

Sign In

Sign In

Book Consultation
Home › IRS Forms › Form 8959

Form 8959: Net Investment Income Tax (NIIT)

Complete professional guide to Form 8959 — calculating the 3.8% Net Investment Income Tax, modified adjusted gross income thresholds, investment income definition, and NIIT avoidance strategies for high-income taxpayers. Updated for 2026.

IRC §1411 3.8% Tax High Income Investment Income MAGI

What Is Form 8959 and the Net Investment Income Tax?

Form 8959, Net Investment Income Tax, is used to calculate the 3.8% Net Investment Income Tax (NIIT) imposed under IRC §1411 on high-income individuals, estates, and trusts. The NIIT was enacted as part of the Affordable Care Act (ACA) and has been in effect since January 1, 2013. The tax applies to the lesser of (1) net investment income or (2) the excess of modified adjusted gross income (MAGI) over the applicable threshold.

The NIIT is NOT part of regular income tax — it is a separate 3.8% tax that applies in addition to ordinary income tax, Medicare payroll taxes, and the additional 0.9% Medicare tax on wages. For high-income taxpayers, the combined effect of NIIT and Medicare taxes can result in effective marginal tax rates exceeding 50% on investment income.

Critical Planning Opportunity

Many high-income taxpayers are unaware of the NIIT or fail to file Form 8959 when required. Practitioners who proactively identify NIIT exposure and recommend avoidance strategies create significant value for clients.

NIIT Thresholds for 2026

Filing Status2026 MAGI Threshold2025 MAGI Threshold
Single$200,000$200,000
Married Filing Jointly$250,000$250,000
Married Filing Separately$125,000$125,000
Qualifying Widow(er)$250,000$250,000
Estates & Trusts$12,950$12,950

Note: The thresholds have NOT been indexed for inflation since 2013. This means more taxpayers are subject to NIIT each year as their incomes grow. Practitioners should monitor MAGI for all high-income clients to identify NIIT exposure early.

What Is Net Investment Income (NII)?

Net investment income includes: (1) interest, dividends, capital gains, and annuities; (2) rental income and royalties (unless derived from an active trade or business); (3) income from passive activities; (4) gains from the sale of investment property; and (5) certain other investment income. NII does NOT include wages, self-employment income from an active trade or business, or distributions from qualified retirement accounts (401(k), IRA, etc.).

The key distinction is between passive and active income. Income from a business in which the taxpayer materially participates is NOT subject to NIIT. This creates significant planning opportunities for business owners and self-employed individuals.

NIIT Avoidance Strategies

1
Roth Conversions — Convert traditional IRA or 401(k) balances to Roth IRAs. While the conversion itself increases MAGI, future Roth growth and distributions are not subject to NIIT.
2
Qualified Dividend & Capital Gains Planning — Harvest losses to offset gains; use tax-loss harvesting to reduce net investment income below the threshold.
3
Active Business Classification — Ensure real estate and other business income is properly classified as active (not passive) to exclude it from NII. This requires material participation under IRC §469.
4
S-Corporation Election — Convert a sole proprietorship or partnership to an S-corporation to classify income as wages (not subject to NIIT) rather than passive income.
5
Charitable Contributions — Donate appreciated securities to charitable remainder trusts (CRTs) or donor-advised funds (DAFs) to reduce MAGI and NII simultaneously.
6
Timing of Income & Deductions — Defer investment income to future years; accelerate deductions into high-income years to reduce MAGI below the threshold.

Frequently Asked Questions — Form 8959 & NIIT

Who must file Form 8959?
Individuals, estates, and trusts must file Form 8959 if their modified adjusted gross income (MAGI) exceeds the applicable threshold AND they have net investment income. For individuals, the thresholds are $200,000 (single), $250,000 (MFJ), $125,000 (MFS), and $250,000 (qualifying widow(er)). For estates and trusts, the threshold is $12,950 (2026). Practitioners should screen all high-income clients for NIIT exposure, as many are unaware of the requirement.
What is modified adjusted gross income (MAGI) for NIIT purposes?
MAGI for NIIT purposes is adjusted gross income (AGI) plus certain excluded items such as foreign earned income exclusions (IRC §911), excluded Puerto Rico income, and excluded Samoa income. For most taxpayers, MAGI equals AGI. However, for taxpayers with foreign income exclusions or other specific exclusions, MAGI may differ from AGI. Form 8959 includes a worksheet to calculate MAGI if applicable exclusions exist.
Is self-employment income subject to the NIIT?
Self-employment income from an active trade or business is NOT subject to NIIT. The key is whether the taxpayer materially participates in the business under IRC §469. If the taxpayer materially participates, the income is excluded from net investment income. However, if the self-employment activity is passive (e.g., a rental property where the taxpayer does not materially participate), the income IS subject to NIIT. Practitioners should carefully analyze whether real estate and other business activities qualify as active or passive.
Are capital gains from the sale of a primary residence subject to NIIT?
No. Capital gains excluded under IRC §121 (up to $250,000 for single filers, $500,000 for MFJ) are not subject to NIIT. However, if the taxpayer has gains exceeding the exclusion amount, the excess is subject to NIIT if MAGI exceeds the threshold. Additionally, capital gains from the sale of investment property (not a primary residence) are subject to NIIT.
How does a Roth conversion affect NIIT?
A Roth conversion increases MAGI in the year of conversion (the conversion amount is added to income), which may trigger or increase NIIT in that year. However, future Roth growth and distributions are not subject to NIIT. Practitioners should model the short-term NIIT cost against the long-term benefit of tax-free Roth growth. In some cases, spreading conversions over multiple years or timing conversions in low-income years can minimize NIIT impact.
Is rental income subject to NIIT?
Rental income is generally subject to NIIT unless the taxpayer materially participates in the rental activity. For most passive real estate investors, rental income is included in net investment income and subject to the 3.8% NIIT if MAGI exceeds the threshold. However, if the taxpayer qualifies as a real estate professional under IRC §469(c)(7), rental income may be classified as active and excluded from NIIT. This is a complex determination that requires detailed analysis of the taxpayer’s involvement in the rental activity.
What is the interaction between NIIT and the Medicare surtax on wages?
NIIT and the additional 0.9% Medicare tax on wages are separate taxes. The 0.9% Medicare tax applies to wages exceeding $200,000 (single) or $250,000 (MFJ). The 3.8% NIIT applies to net investment income. A high-income taxpayer can be subject to both taxes simultaneously. Combined with the 3.8% NIIT, the 0.9% Medicare tax, and ordinary income tax rates, the effective marginal tax rate on investment income can exceed 50% for top earners in high-tax states.
How should a business owner structure their entity to minimize NIIT?
A business owner can minimize NIIT by electing S-corporation status (if eligible). In an S-corporation, the owner receives a W-2 wage for services rendered, and the remaining profit is distributed as a dividend. The W-2 wages are not subject to NIIT (though they are subject to payroll taxes). The dividend portion may be subject to NIIT if MAGI exceeds the threshold, but the W-2 wage portion is excluded. This creates an opportunity to shift income from investment income (subject to NIIT) to wages (not subject to NIIT), though payroll taxes must be considered.
Are distributions from a 401(k) or traditional IRA subject to NIIT?
Distributions from qualified retirement plans (401(k), 403(b), traditional IRA) are NOT subject to NIIT. However, the distributions are included in MAGI for purposes of determining whether the taxpayer exceeds the NIIT threshold. This means that a retiree with significant retirement plan distributions may exceed the MAGI threshold and become subject to NIIT on other investment income (such as dividends and capital gains) even though the retirement distributions themselves are not subject to NIIT.
What is the deadline to file Form 8959?
Form 8959 is filed with the individual’s Form 1040 (or Form 1041 for estates and trusts). The deadline is April 15 of the following year (or October 15 if an extension is filed). Practitioners should ensure that high-income clients file Form 8959 if required, as failure to file can result in accuracy-related penalties.
Can NIIT be reduced through charitable giving strategies?
Yes. Charitable contributions reduce AGI and MAGI, which can reduce NIIT exposure. Donating appreciated securities to a charitable remainder trust (CRT) or donor-advised fund (DAF) can eliminate capital gains tax on the appreciated securities while also reducing MAGI. For example, a donor who donates $100,000 of appreciated stock to a DAF can avoid capital gains tax on the appreciation and reduce MAGI by $100,000, potentially reducing NIIT by $3,800 (3.8% of the MAGI reduction).
Are qualified dividends and long-term capital gains taxed differently under NIIT?
For purposes of calculating net investment income on Form 8959, qualified dividends and long-term capital gains are included at their full amount (not at preferential rates). The preferential tax rates (0%, 15%, 20%) apply to the net investment income after NIIT is calculated. This means that NIIT applies to the full amount of qualified dividends and long-term gains, even though those items are taxed at preferential rates for regular income tax purposes. This creates a situation where high-income taxpayers pay both NIIT (3.8%) and preferential rate income tax (15-20%) on the same investment income.
Professional Disclaimer

The information on this page is intended for licensed tax professionals (CPAs, EAs, and tax attorneys) and is provided for educational and research purposes only. Tax law is complex and fact-specific — all strategies discussed are subject to limitations, phase-outs, and conditions that may not apply to every client situation. Practitioners should independently verify all information against current IRS guidance, Treasury Regulations, and applicable state law before advising clients. This content does not constitute legal or tax advice.

High-Income Clients Need NIIT Planning

Tax Clients Are on Uncle Kam. Join the Marketplace and Grow Your Practice.

Uncle Kam connects tax professionals with pre-qualified business owner clients who are ready to pay for advisory services. Join the marketplace, get matched with clients in your state, and grow your practice without cold outreach.

Apply to Join the Marketplace → See How Tax Pros Use This
Free access to 300+ tax strategies Join the Marketplace →

Related Resources

Explore our tax professional directory and deduction guides.

CPA Near Me Tax Accountant Near Me Tax Strategist Near Me Accountant Near Me Tax Write-Offs Guide Tax Preparation Services 2026 Tax Changes