Capital Gains Tax Harvesting (0% Long-Term Bracket) Optimizer
Determine exactly how much long-term stock gain you can realize at 0% federal tax rate, locking in a permanently higher cost basis.
Under IRC § 1(h), long-term capital gains are taxed at 0% for married couples with taxable income up to $96,700 ($48,350 for singles) in 2025. Tax-gain harvesting allows you to intentionally sell appreciated stocks and immediately repurchase them at a higher cost basis, paying $0 in federal taxes and resetting your capital gains clock.
Scenario Parameters
0% Long-Term Capital Gains Bracket Headroom & Tax Savings
How the Capital Gains Tax Harvesting (0% Long-Term Bracket) Optimizer Works: Plain-English US Tax Guide
When you hold capital assets (stocks, ETFs, mutual funds, real estate) for longer than one year, profits are taxed at favorable Long-Term Capital Gains (LTCG) tax rates: 0%, 15%, or 20%.
The 0% Federal Capital Gains Bracket (2025 Statutory Limits): - Up to $48,350 of taxable income for Single filers. - Up to $96,700 of taxable income for Married Filing Jointly. - Up to $64,750 for Head of Household.
How Long-Term Gains 'Stack' on Top of Ordinary Income: Your ordinary income (W-2 salary, pensions, interest, short-term gains) sits at the bottom of your tax bracket stack. Long-term capital gains stack on top. If your ordinary taxable income is below the 0% LTCG threshold, you can harvest capital gains tax-free until the top of the 0% bracket!
Tax-Gain Harvesting vs. Wash-Sale Rules: Unlike tax-loss harvesting—where the IRS Wash-Sale Rule (IRC § 1091) forbids buying the same stock within 30 days—there is NO wash-sale rule for capital gains! You can sell an appreciated stock at 10:00 AM to lock in a 0% federal tax gain, and repurchase the identical stock at 10:01 AM. You immediately step up your cost basis to the current market price with zero tax liability, shielding future growth from taxes forever.
This calculator computes your remaining 0% tax-gain harvesting headroom before crossing into the 15% bracket or the 3.8% Net Investment Income Tax (NIIT).
Case Study: Early Retiree Married Couple Harvesting $32,000 in Stock Gains at 0% Tax
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0% LTCG Bracket Limit for MFJ: $96,700.
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Ordinary Taxable Income: $50,000.
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Available 0% Harvesting Headroom: $96,700 - $50,000 = $46,700 in capital gains space.
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Execution: They sell $32,000 in long-term index fund gains and immediately buy back the same funds.
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Taxes Owed: $0 in federal capital gains taxes. Their cost basis is permanently increased by $32,000.
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Future Savings: When they sell these shares years later in the 15% bracket, they will avoid $4,800 ($32,000 * 15%) in future federal taxes.
Key 2025 / 2026 Statutory Thresholds & IRS Rules
| Statutory Provision / Rule | 2025 / 2026 Benchmark | Impact on US Taxpayers |
|---|---|---|
| 2025 0% LTCG Threshold | $48,350 Single / $96,700 MFJ | Taxable income threshold below which long-term capital gains are taxed at 0%. |
| No Wash-Sale Rule for Gains | Instant Repurchase Allowed | IRS wash-sale rules apply strictly to losses; gain harvesting permits instant rebuy. |
| Net Investment Income Tax (NIIT) | 3.8% over $200k / $250k | Applies to net investment income once MAGI crosses statutory thresholds under IRC § 1411. |
| State Income Tax Warning | State Tax Still Applies | Most states (e.g. CA, NY) do not offer a 0% capital gains rate; gains are taxed as ordinary state income. |
Costly Mistakes & IRS Tax Traps to Avoid
Gains harvested beyond the 0% threshold are taxed at 15% federal capital gains rate.
Capital gains increase your MAGI for the year, which can reduce your ACA health insurance premium tax credits.
Harvesting gains increases 'provisional income', which can cause up to 85% of your Social Security benefits to become taxable.
Statutory Audit Trail & Policy Context
| Calculation Step / IRC Statutory Line | Amount ($) | Tax Policy Authority & Notes |
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Federal Preemption & Multi-State Application
This calculator operates under federal IRS statutory guidelines (Internal Revenue Code). Federal rules apply uniformly across all 50 states, while local modifications (such as state income tax deductions or exemptions) are reflected in the net take-home and audit trail calculations.