The Section 1411 Adjustment — Decoding the 3.8% Surtax Line
Dwaine Clarke · NNN Deal Finder / GCT Commercial
Published July 16, 2026
Section 1411 is the net investment income tax — the 3.8% surtax layered onto investment income above the thresholds — and the “adjustment” is how pass-throughs reconcile your share of it. For rental owners it’s a permanent tenant in the tax return, so it’s worth understanding once, properly.
Who pays, on what
The NIIT applies when modified AGI exceeds $200K (single) or $250K (joint) — thresholds never indexed, so inflation drafts more landlords annually. Net investment income includes interest, dividends, capital gains, and — squarely — rental income and gains from rental sales. The tax is 3.8% of the lesser of your net investment income or your MAGI excess over the threshold.
The rental nuances that matter
Passive rental income — the default for NNN owners — is NIIT income. Real estate professionals (750+ hours, more than half of working time in real property trades, material participation) can exclude rental income earned in that capacity — the major escape hatch, with substantiation requirements the IRS actually audits. The self-rental and grouping rules rescue some operators who rent to their own businesses. And on sale, the taxable gain (including recaptured depreciation) is NIIT-exposed for passive holders — making the effective top federal rate on a big rental sale 23.8% on capital gain and 28.8% on recapture before state tax.
Where the adjustment shows up
Entity K-1s carry NIIT information (commonly Box 20 code Y on partnership returns, with attached detail); your preparer maps it onto Form 8960. When the adjustment is negative, the entity is often backing out income that’s non-investment at your level; positive, the reverse. If a K-1’s 1411 detail arrives blank or contradictory — common with syndications — request the supplemental schedule early rather than extending in October.
Planning levers
The realistic ones: qualify (legitimately) as a real estate professional; manage MAGI in sale years — which is one more argument for 1031 deferral over cash sales; harvest investment losses against investment gains; and mind installment-sale pacing, since spreading gain across years can keep MAGI under the threshold repeatedly. None of this is exotic — it’s sequencing, and the sequencing is your CPA’s craft. Our lane is the property side: income structured to survive taxes starts with income durable enough to bother taxing.