New Mexico Capital Gains Tax, Explained

New Mexico doesn't run a separate capital gains schedule. Instead, Section 7-2-34 gives every taxpayer a deduction against net capital gain income before it's taxed at ordinary rates, and the deduction has two very different tracks. You claim whichever is larger:

Track one, the general deduction: your net capital gain for the year, dollar for dollar, up to a $2,500 cap. This applies to any capital asset, stock, a second home, a rental, cryptocurrency, whatever generated the gain.

Track two, the business-sale deduction: 40% of up to $1,000,000 of net capital gain, but only if that gain comes from the sale of a business allocated or apportioned to New Mexico under the state's apportionment rules. The maximum deduction under this track is $400,000.

Worked example: an investor sells a stock position for a $200,000 long-term gain. The general deduction is capped at $2,500, so $197,500 is taxable, about $11,652 in New Mexico tax at the 5.9% top rate. A business owner who sells a qualifying New Mexico business for the identical $200,000 gain deducts 40% of it, $80,000, leaving $120,000 taxable, about $7,080 in state tax. Same gain, same top bracket, a $4,572 difference purely because of which deduction track the sale qualifies for.

Whatever portion of your gain the Section 7-2-34 deduction doesn't shield gets added to your other New Mexico income and taxed at the state's regular graduated brackets. New Mexico restructured its brackets for tax years beginning in 2025, and the same structure carries into 2026: six rates running from 1.5% up to 5.9% at the top.

For single filers, the 5.9% top rate applies to taxable income above $210,000. For married couples filing jointly, it applies above $315,000. Below those thresholds, lower graduated rates (1.5%, 3.2%, 4.3%, 4.7%, and 4.9%) apply in bands, so a moderate gain stacked on modest other income often lands well under the headline 5.9%.

Because New Mexico has no separate capital gains rate, holding period only matters through the federal system and through Section 7-2-34's definition of "net capital gain," which follows the federal long-term definition (assets held over one year). A short-term gain doesn't qualify for either deduction track and is fully ordinary income at your New Mexico bracket.

New Mexico's deduction only ever touches the state return. Federally, your gain is still taxed under its own rules: 0%, 15%, or 20% for long-term gains depending on your bracket, ordinary rates up to 37% for short-term gains, and the 3.8% net investment income tax layered on above $200,000 MAGI for single filers or $250,000 for married filing jointly.

Put both layers together: a $300,000 long-term investment gain taxed at the federal 15% bracket costs about $45,000 federally. After New Mexico's $2,500 general deduction, it costs about $17,552 to the state at the 5.9% top rate, a combined effective rate near 20.9%. Add the NIIT for a higher-income seller and the combined number climbs further, since neither the federal nor the state calculation offers relief beyond the capped deduction.

Everything that reduces the federal gain, loss harvesting, gain timing into a lower-income year, or an installment sale that spreads income across years, reduces the New Mexico number in the same motion, since the state deduction applies to whatever net capital gain shows up on the federal return.

A rental or investment property sale splits into two pieces for New Mexico purposes, and only one of them touches Section 7-2-34's deduction. The gain attributable to depreciation you claimed while renting the property comes back as recapture. Recapture is ordinary income for federal purposes, not the net capital gain defined in IRC Section 1222(11) that Section 7-2-34 references, so it doesn't qualify for the $2,500 general deduction (and it's never a business sale under the 40% track either). It's taxed in full at your ordinary New Mexico bracket.

The remaining piece, appreciation above your depreciated basis, is what actually qualifies as long-term capital gain, eligible for the $2,500 general deduction if you held the property more than a year.

Worked example: you sell a rental for a $180,000 total gain, of which $50,000 is depreciation recapture and $130,000 is appreciation, in the top federal and New Mexico brackets. Federally: $50,000 x 25% recapture rate = $12,500, plus $130,000 x 15% assumed LTCG bracket = $19,500. In New Mexico: the $50,000 recapture is taxed in full at 5.9% = $2,950; the $130,000 appreciation gets the $2,500 deduction, leaving $127,500 taxable at 5.9% = $7,522. New Mexico total: $10,472. The deduction only ever reached the appreciation slice.

Since the 2025 rewrite, the 40%-of-up-to-$1,000,000 deduction is available only for net capital gain from the sale of a business that is allocated or apportioned to New Mexico under the state's standard apportionment statute, Section 7-2-11 NMSA 1978. This is the sourcing rule that determines how much of a multi-state business's income counts as New Mexico's for tax purposes, and it now gates the state's single largest capital gains break.

For an owner whose business operates entirely in New Mexico, apportionment is usually a formality, most or all of the gain sources to the state. For an owner with operations, payroll, or sales spread across multiple states, only the New Mexico-apportioned share of the gain qualifies for the 40% deduction; the rest falls back to ordinary treatment with no deduction beyond what's left of the $2,500 general cap.

One more mechanical detail: married couples who file separate returns in a year they could have filed jointly can each claim only half of whatever deduction would have applied on a joint return, under both tracks. That's a filing-status choice worth modeling before a large sale closes, not after.