Capital Gains Net Investment Income Tax (NIIT) Calculator

What is the current Net Investment Income Tax rate?

The current Net Investment Income Tax (NIIT) rate is 3.8%. This flat surtax applies to individuals, estates, and trusts that have net investment income and a Modified Adjusted Gross Income (MAGI) that exceeds certain statutory threshold amounts.

What income thresholds trigger the NIIT for different filing statuses?

The NIIT is triggered when your Modified Adjusted Gross Income (MAGI) exceeds specific statutory thresholds based on your tax filing status. These thresholds are not adjusted annually for inflation.

How do you calculate Modified Adjusted Gross Income for NIIT purposes?

For the purpose of calculating the Net Investment Income Tax, Modified Adjusted Gross Income (MAGI) is determined through the following steps:

1. Start with your standard Adjusted Gross Income (AGI) as reported on Form 1040.
2. Add back any foreign earned income exclusion claimed under Section 911.
3. Add back any foreign housing exclusion or deduction.
4. Subtract any deductions previously taken related to the foreign earned income.

For individuals living in the U.S. who do not have foreign income, their MAGI for NIIT purposes is typically identical to their standard AGI.

Which specific types of capital gains are subject to the NIIT?

Most taxable capital gains are included in your Net Investment Income. Specific types of capital gains subject to the NIIT include:

• Gains from the sale of financial assets like stocks, bonds, and mutual funds.
• Gains from the sale of investment real estate or second homes.
• Capital gain distributions paid out by mutual funds.
• Gains from the sale of interests in partnerships and S corporations (if you are considered a passive investor).

Does the NIIT apply to both short-term and long-term capital gains?

Yes, the Net Investment Income Tax applies to both short-term and long-term capital gains. While the standard income tax system rewards long-term investments with favorable, lower tax rates, the 3.8% NIIT is a flat surtax applied equally to both short-term and long-term capital gains, provided your income exceeds the required threshold.

Are capital gains from selling a primary residence subject to this tax?

Capital gains from the sale of a primary residence are only subject to the NIIT if the gain exceeds the Section 121 home sale exclusion limit. This tax code provision allows you to exclude up to $250,000 (Single) or $500,000 (Married Filing Jointly) of capital gain from your gross income. Only the taxable portion of the gain that strictly exceeds these exclusion limits is included in your net investment income and potentially subjected to the 3.8% tax.

Can capital losses be used to reduce your NIIT liability?

Yes, capital losses can be utilized to reduce your Net Investment Income Tax liability. When calculating your total Net Investment Income, you can offset your capital gains with your capital losses. If your capital losses exceed your capital gains, you can use up to $3,000 (or $1,500 if Married Filing Separately) of that excess loss to offset other types of investment income, such as interest or dividends, mirroring standard capital loss rules.

Are distributions from traditional or Roth retirement accounts subject to the NIIT?

No, distributions from qualified retirement accounts are specifically exempt from the Net Investment Income Tax. This includes distributions from:

• Traditional and Roth IRAs
• 401(k), 403(b), and 457(b) plans
• Pensions and profit-sharing plans

However, it is important to note that while these distributions are not taxed directly by the NIIT, taxable distributions (like those from a traditional 401k) will increase your MAGI. This could push you over the statutory threshold and subject your other non-retirement investment income to the NIIT.

Is the tax calculated on your total investment income or just the amount over the threshold?

The NIIT is not automatically applied to your total investment income. Instead, the 3.8% tax is calculated on the lesser of two amounts:

1. Your total Net Investment Income (NII) for the year.
2. The exact amount by which your Modified Adjusted Gross Income (MAGI) exceeds the statutory threshold for your filing status.

For example, if you have $50,000 in NII but your MAGI is only $10,000 over your filing status threshold, you will only pay the 3.8% tax on the $10,000 excess.

What specific IRS tax form is required to report the Net Investment Income Tax?

Taxpayers must use IRS Form 8960 (Net Investment Income Tax—Individuals, Estates, and Trusts) to calculate their NII and determine if they owe the tax. If a liability is calculated, the final amount from Form 8960 is carried over and reported on Schedule 2 (Form 1040), under "Additional Taxes," which is attached to your main tax return.

Sources:

• IRS: Questions and Answers on the Net Investment Income Tax
• Investopedia: Net Investment Income (NII) Definition
• IRS: About Form 8960, Net Investment Income Tax

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