The Net Investment Income Tax is imposed by section 1411 of the Internal Revenue Code. The NIIT applies at a rate of 3.8% to certain net investment income of individuals, estates and trusts that have income above the statutory threshold amounts.
In general, investment income includes, but is not limited to: interest, dividends, capital gains, rental and royalty income, non-qualified annuities, income from businesses involved in trading of financial instruments or commodities and businesses that are passive activities to the taxpayer (within the meaning of section 469). To calculate your Net Investment Income, your investment income is reduced by certain expenses properly allocable to the income.
To the extent that gains are not otherwise offset by capital losses, the following gains are common examples of items taken into account in computing Net Investment Income:
- Gains from the sale of stocks, bonds, and mutual funds.
- Capital gain distributions from mutual funds.
- Gain from the sale of investment real estate (including gain from the sale of a second home that is not a primary residence).
- Gains from the sale of interests in partnerships and S corporations (to the extent the partner or shareholder was a passive owner)
The Net Investment Income Tax does not apply to any amount of gain that is excluded from gross income for regular income tax purposes. The pre-existing statutory exclusion in section 121 exempts the first $250,000 ($500,000 in the case of a married couple) of gain recognized on the sale of a principal residence from gross income for regular income tax purposes and, thus, from the NIIT.
Example 1: A, a single filer, earns $210,000 in wages and sells his principal residence that he has owned and resided in for the last 10 years for $420,000. A’s cost basis in the home is $200,000. A’s realized gain on the sale is $220,000. Under section 121, A may exclude up to $250,000 of gain on the sale. Because this gain is excluded for regular income tax purposes, it is also excluded for purposes of determining Net Investment Income. In this example, the Net Investment Income Tax does not apply to the gain from the sale of A’s home.
Example 2: B and C, a married couple filing jointly, sell their principal residence that they have owned and resided in for the last 10 years for $1.3 million. B and C’s cost basis in the home is $700,000. B and C’s realized gain on the sale is $600,000. The recognized gain subject to regular income taxes is $100,000 ($600,000 realized gain less the $500,000 section 121 exclusion). B and C have $125,000 of other Net Investment Income, which brings B and C’s total Net Investment Income to $225,000. B and C’s modified adjusted gross income is $300,000 and exceeds the threshold amount of $250,000 by $50,000. B and C are subject to NIIT on the lesser of $225,000 (B’s Net Investment Income) or $50,000 (the amount B and C’s modified adjusted gross income exceeds the $250,000 married filing jointly threshold). B and C owe Net Investment Income Tax of $1,900 ($50,000 X 3.8%).
Example 3: D, a single filer, earns $45,000 in wages and sells her principal residence that she has owned and resided in for the last 10 years for $1 million. D’s cost basis in the home is $600,000. D’s realized gain on the sale is $400,000. The recognized gain subject to regular income taxes is $150,000 ($400,000 realized gain less the $250,000 section 121 exclusion), which is also Net Investment Income. D’s modified adjusted gross income is $195,000. Since D’s modified adjusted gross income is below the threshold amount of $200,000, D does not owe any Net Investment Income Tax.