Northern Mariana Islands capital gains tax calculator

A resident pays two taxes on a gain. The earnings tax takes the gain on shares, funds, crypto or unlisted stakes in full, or half the gain on CNMI real property, at a rate from 2% to 9% of the whole amount (9% once the year's earnings pass $50,000). The Northern Marianas Territorial Income Tax, the U.S. Internal Revenue Code applied locally, charges 0%, 15% or 20% on long-term gains, ordinary rates on short-term gains and the 3.8% net investment income tax. The earnings tax is credited against the territorial income tax, and a rebate of 90%, then 70%, then 50% of what remains cuts it further. For a top-bracket resident that leaves 16.4 cents of tax on each extra dollar of long-term gain.

A resident files Form 1040CM and Form NMI-A with the CNMI Division of Revenue and Taxation by 15 April. Schedule OS-3405A claims the credit for the earnings tax and the rebate.

Capital losses offset capital gains for the territorial income tax without limit. A net capital loss deducts at most $3,000 ($1,500 married filing separately) against ordinary income each year, and the rest carries forward indefinitely. The earnings tax gets no loss offset: 4 CMC 1202(d) says a person shall not reduce any earnings by any loss, so each gain is charged on its own.

The Northern Mariana Islands taxes its residents under a mirror code: the U.S. Internal Revenue Code is adopted as the Northern Marianas Territorial Income Tax (NMTIT), the U.S. rate schedule applies with 'Commonwealth of the Northern Mariana Islands' read for 'United States' (4 CMC 1701(a), (e), at https://cnmilaw.gov/legacy/pdf/cmc_section/T4/1701.pdf), and the CNMI Division of Revenue and Taxation collects it on Form 1040CM (https://www.finance.gov.mp/division-forms/revenue-taxation/2025/f1040cm--2025.pdf).

Long-term capital gains (a capital asset held more than one year, IRC 1222(3)) are taxed 0/15/20 by taxable income. The breakpoints for 2026 are the section 1(j)(5) maximum zero-rate and maximum 15% amounts of Rev. Proc. 25-32: single 49,450/545,500, joint 98,900/613,700, separate 49,450/306,850, head of household 66,200/579,600. The gain stacks on top of ordinary taxable income plus net short-term gain (Schedule D Tax Worksheet order). The 20% top rate is statutory (IRC 1(h)(1)(D)).

Net short-term capital gains (held one year or less) are taxed as ordinary income at graduated rates; they fill the ordinary brackets, not the 0/15/20 schedule. A gain is long-term only when the asset is held more than one year, counting from the day after acquisition to the day of disposal (IRS Topic 409), so a sale on the exact first anniversary is short-term.

The earnings tax (4 CMC 1202) charges a resident the chapter 2 schedule on a gain from the sale of personal property (shares, funds, crypto, unlisted stakes) that was not in the course of a business, and on one half of the gain from the sale of real property in the Commonwealth. The schedule is 4 CMC 1204: $1,000 or less nothing, then 2%, 3%, 4%, 5%, 6%, 7%, 8% and 9% of the WHOLE amount as the total passes $5,000, $7,000, $15,000, $22,000, $30,000, $40,000 and $50,000 (statute at https://cnmilaw.gov/legacy/pdf/cmc_section/T4/1202.pdf and https://cnmilaw.gov/legacy/pdf/cmc_section/T4/1204.pdf; the 2025 Form 1040CM, Form NMI-A and Schedule OS-3405A use the same lines at https://www.finance.gov.mp/division-forms/revenue-taxation/2025/f1040cm--2025.pdf).

A loss never reduces earnings: 'In determining the total earnings, a person shall not reduce any earnings by any loss' (4 CMC 1202(d)). The earnings tax is charged on the year's gains even when losses leave no gain for the territorial income tax.

The earnings tax paid is a nonrefundable credit against the NMTIT on Commonwealth-source income (4 CMC 1206). What is left, the rebate base, is cut by the rebate offset of 4 CMC 1708(b)(1)(i): 90 percent of the base up to $20,000, $18,000 plus 70 percent of the base over $20,000 up to $100,000, and $74,000 plus 50 percent over $100,000 (https://cnmilaw.gov/legacy/pdf/cmc_section/T4/1708.pdf; Schedule OS-3405A prints the same table). A gain on personal property by a resident is sourced to the Commonwealth (IRC 865 by mirror), so it sits in the rebate base.

Capital losses net capital gains without limit; a net capital loss deducts at most $3,000 ($1,500 married filing separately) against ordinary income (IRC 1211(b)) and the excess carries forward to later years without a time limit (IRC 1212(b)).

The 3.8% net investment income tax (IRC 1411) is part of the mirrored code; the Form 1040CM line for other taxes excludes only Schedule 2 Part II lines 4, 5, 6, 7, 9, 11, 13 and 17m (https://www.finance.gov.mp/division-forms/revenue-taxation/2025/f1040cm--2025.pdf), which leaves the section 1411 line in the return. It charges 3.8% of the lesser of net investment income or the excess of modified adjusted gross income over $250,000 joint / $125,000 separate / $200,000 otherwise (IRC 1411(b)), and sits inside the NMTIT that the credit and the rebate then reduce.

Wash sales (IRC 1091): a loss on stock or securities is disallowed where substantially identical stock or securities were bought within the 30 days before or after the sale; the disallowed loss adds to the basis of the replacement shares.

The main-home exclusion (IRC 121) applies to the NMTIT through the mirror: $250,000 of gain excluded ($500,000 on a joint return) on a principal residence owned and used two of the last five years, once every two years. The earnings tax reads the gain 'as determined under NMTIT section 1001' (4 CMC 1202(b)(2)), so half of the full home gain, exclusion not deducted, remains subject to it.

Not modelled: the 25% rate on unrecaptured section 1250 gain, the 28% maximum on collectibles and section 1202 qualified small business stock, gains sourced outside the Commonwealth (which carry no earnings tax and no rebate), the education tax credit of 4 CMC 1205 and the de minimis exemption of 4 CMC 1202(c).