TCJA Sunset Capital Gains & NIIT Tax Simulator 2027

Statutory threshold comparison and code references governing capital asset dispositions pre- and post-sunset.

Capital Gains Optimization Strategy for the Post-TCJA Era

While the Tax Cuts and Jobs Act of 2017 centered its individual tax reforms on ordinary income brackets and standard deductions, its impending statutory sunset on December 31, 2025 directly impacts capital gains tax planning through income stacking interactions. Under Internal Revenue Code Section 1(h), long-term capital gains are layered on top of ordinary income, meaning any increase in ordinary tax liability or bracket compression shifts capital gains into higher marginal territory earlier.

Furthermore, high-earning investors must contend with the Section 1411 Net Investment Income Tax (NIIT). Enacted under the Affordable Care Act, the NIIT imposes an unindexed 3.8% surtax on net investment income for single filers with modified adjusted gross income exceeding $200,000 ($250,000 for married joint filers). Because these thresholds were intentionally excluded from annual inflation adjustments, fiscal drag causes an increasing percentage of mid-career professionals and startup equity holders to trigger the surtax each year.

To mitigate exposure prior to the sunset, taxpayers should evaluate multi-year tax loss harvesting, installment sales under IRC Section 453, and charitable remainder unitrusts (CRUTs) to defer or smooth capital asset dispositions across calendar years.