Capital Gains Tax Math: Short-Term vs. Long-Term Rates & Tax-Loss Harvesting Strategies
Written by Elena Rostova, CPA
Understanding Capital Gains Taxation
When you sell taxable investments—such as stocks, ETFs, crypto, or real estate—for a profit, the IRS taxes the profit as a **capital gain**. However, not all capital gains are taxed equally. The single biggest determining factor of your tax liability is your **holding period**.
The internal revenue code creates two distinct tax categories for realized investment profits:
- Short-Term Capital Gains (Held ≤ 365 Days): Taxed as ordinary income at your full marginal tax rate (10%, 12%, 22%, 24%, 32%, 35%, or 37%).
- Long-Term Capital Gains (Held > 365 Days): Taxed at preferential long-term capital gains rates (0%, 15%, or 20%), saving investors significant capital.
The Federal Long-Term Capital Gains Brackets (2026 Single Filers)
| Cap Gains Rate | Taxable Income Range (Single Filer) | Taxable Income Range (Married Filing Jointly) |
|---|---|---|
| 0% Rate | $0 to $48,350 | $0 to $96,700 |
| 15% Rate | $48,350 to $533,400 | $96,700 to $600,050 |
| 20% Rate | > $533,400 | > $600,050 |
The Mechanics of Tax-Loss Harvesting
**Tax-loss harvesting** is the strategic realization of investment losses to offset taxable capital gains and ordinary income. Under IRS ordering rules:
- Short-term losses first offset short-term gains.
- Long-term losses first offset long-term gains.
- Any net remaining loss offsets the opposite gain type.
- If total losses exceed total gains, you can offset up to **$3,000 of ordinary income** per year, carrying forward any remaining losses indefinitely!
Worked Example: Tax-Loss Harvesting Calculation
Let's model an investor, Rachel, in the **24% ordinary marginal tax bracket** who realizes the following trades in her taxable brokerage account:
- Trade A (Realized Short-Term Gain): +$10,000 profit on tech stock held 6 months.
- Trade B (Realized Short-Term Loss): -$8,000 loss on biotech stock held 4 months.
- Trade C (Realized Long-Term Loss): -$5,000 loss on index fund held 2 years.
Net Short-Term = +$10,000 - $8,000 = +$2,000 Short-Term Gain.
Remaining Net = +$2,000 Short-Term Gain - $5,000 Long-Term Loss = -$3,000 Net Loss.
The entire -$3,000 net loss directly offsets $3,000 of her ordinary W-2 salary!
Because Rachel harvested these losses, she eliminated the **24% ordinary tax** on her $2,000 short-term gain ($480 saved) AND reduced her ordinary taxable salary by $3,000 ($720 saved). In total, tax-loss harvesting saved her **$1,200 in cash taxes**!
The Wash-Sale Rule Warning
To claim a loss, you must avoid the **Wash-Sale Rule**. If you buy a "substantially identical" security within **30 days before or after** the sale, the loss is disallowed for the current tax year and added to the cost basis of the new asset.
Key Takeaways
- Hold Past 365 Days: Transitioning profits from short-term to long-term status cuts your tax rate from up to 37% down to 15%.
- Harvest $3,000 Annually: Utilize net capital losses to offset high-bracket ordinary income each tax year.
- Respect the 30-Day Window: Wait 31 days or substitute with a non-identical asset to satisfy wash-sale regulations.
Disclaimer: This article is for educational purposes only and does not constitute formal financial, investment, or legal advice. Always speak with a certified advisor before making capital allocations.
Ready to calculate your tax obligations? Model your marginal brackets and capital taxes using our Marginal Tax & Capital Gains Calculators under Taxes!