Tax Loss Harvesting Estimator

How to Use This Tool

Enter your original purchase price (cost basis) and the current market value of the investment you plan to sell. Add any other realized capital gains you have already locked in this year, then input your applicable capital gains and ordinary income tax rates. Select your filing status to ensure accurate IRS limit tracking. Click Calculate to see your estimated tax savings, loss allocation, and any carryover amount.

Formula and Logic

The estimator follows standard IRS tax loss harvesting rules. First, it calculates your realized loss by subtracting the current market value from the initial cost basis. It then applies that loss against your other realized capital gains for the year, dollar for dollar. Any remaining loss can offset up to $3,000 of ordinary income. If your total loss exceeds both your capital gains and the $3,000 ordinary income limit, the remainder carries forward indefinitely to future tax years. Tax savings are computed by multiplying the offset amounts by your respective marginal tax rates.

Practical Notes

• Watch for wash sales: repurchasing a substantially identical security within 30 days before or after the sale will disallow the loss for tax purposes.
• Short-term losses offset short-term gains first, which are typically taxed at higher ordinary income rates, making them highly valuable for tax planning.
• Keep detailed trade records and broker statements to accurately track cost basis, especially after stock splits, dividends, or multiple purchases.
• Consider compounding effects: reinvesting the tax savings into diversified assets can accelerate long-term portfolio growth.
• Review your overall budget and cash flow before selling, as harvesting losses reduces your current portfolio value even if it lowers your tax bill.

Why This Tool Is Useful

Tax loss harvesting requires precise math and a clear understanding of how different tax brackets interact. This estimator removes guesswork by showing exactly how much of your loss offsets gains, how much reduces ordinary income, and what carries forward. It helps investors make data-driven decisions during market downturns or year-end portfolio rebalancing, ensuring they maximize after-tax returns without violating IRS guidelines.

Frequently Asked Questions

Can I harvest losses in a retirement account?

No. Tax loss harvesting only applies to taxable brokerage accounts. Gains and losses inside IRAs, 401(k)s, and other tax-advantaged accounts do not trigger immediate tax events, so harvesting strategies do not apply there.

What happens if my losses exceed $3,000 in a single year?

Any unused loss beyond the $3,000 ordinary income deduction limit carries forward to the next tax year. You can continue applying it against future capital gains and up to $3,000 of ordinary income each year until the loss is fully utilized.

Does this tool account for state income taxes?

This estimator focuses on federal tax calculations. State tax rules vary significantly, and some states do not allow capital loss deductions or have different limits. Consult a local tax professional to factor in your specific state obligations.

Additional Guidance

Effective tax planning goes beyond a single transaction. Pair loss harvesting with strategic asset location, regular portfolio rebalancing, and long-term compounding strategies. Maintain a disciplined approach by reviewing your holdings quarterly, documenting every trade, and aligning tax moves with your broader financial goals. When in doubt, work with a certified financial planner or CPA to ensure compliance and optimize your overall tax efficiency.