Capital Gains Tax Calculator
Estimate 2026 federal tax on short-term and long-term capital gains using correct LTCG stacking, 0%/15%/20% rates, and Net Investment Income Tax (3.8%).
Long-term capital gains (assets held more than one year) are taxed at preferential rates: 0%, 15%, or 20%, depending on where the gains stack above your ordinary taxable income. These rates are set by IRC §1(h), made permanent by OBBB §70101. 2026 thresholds are from IRS Rev. Proc. 2025-32 §3.03.
The critical concept is stacking: LTCG sits on top of ordinary income. If your ordinary taxable income already reaches the 15% threshold, all your gains are taxed at 15% (or 20% if they push into the 20% zone). Short-term gains are ordinary income, taxed at your marginal bracket rate. The Net Investment Income Tax (NIIT) adds 3.8% on top when MAGI exceeds $200,000 Single / $250,000 MFJ (IRC §1411, unaffected by OBBB).
Worked example: single filer, $50,000 ordinary taxable income, $20,000 LTCG. Stack base = $50,000. 0% threshold (2026, Single) ≈ $50,400. LTCG at 0%: min($20K, $400) = $400; LTCG at 15%: $19,600. Tax on gains = $0 + $2,940 = $2,940 (14.7% effective rate on LTCG).
How to use this calculator
- Enter your ordinary taxable income before gains — this determines where your LTCG stacks.
- Enter your long-term capital gain and/or short-term gain.
- Enter MAGI to check for NIIT (3.8%).
- Use advanced inputs for sale price, basis, and asset-type-specific warnings.
Formula and assumptions
LTCG rates stack on top of ordinary taxable income: 0% band: from max(ordinaryIncome, 0) to $49,450 (Single 2026) 15% band: from $49,450 to $553,850 20% band: above $553,850 NIIT = 3.8% * min(netInvestmentIncome, max(0, MAGI - threshold)) threshold: $200K Single, $250K MFJ, $125K MFS
- 2026 LTCG thresholds
- Single: $49,450 / $553,850 (Rev. Proc. 2025-32)
- MFJ thresholds
- $98,900 / $622,050
- NIIT
- 3.8% on investment income above MAGI threshold
- State tax
- Not included
Worked example
Single, $60,000 ordinary income, $20,000 LTCG, $80,000 MAGI
Limitations
- Does not automatically apply Section 121 home exclusion — enter net taxable gain.
- Collectibles (28% max) and Sec. 1250 recapture (25% max) flagged but not precisely calculated.
- Wash sale rules and installment sales not modeled.
- State capital gains tax not included.
Frequently asked questions
Long-term capital gains are taxed at 0%, 15%, or 20% in 2026 depending on where they stack above your ordinary income. The NIIT adds 3.8% for high earners. Short-term gains are ordinary income.
Recent updates
- Feb 20262026 LTCG thresholds updated from IRS Rev. Proc. 2025-32 §3.03; NIIT thresholds confirmed unchanged.
- Jul 2025OBBB §70101 confirmed LTCG 0%/15%/20% structure permanent; removed prior sunset caveat.
- Nov 2024Initial launch with 2025 LTCG thresholds from Rev. Proc. 2024-61.