Tax loss harvesting calculator

• Harvested losses offset your realized gains first, at the federal capital gains rate you enter plus your state rate. A net loss then offsets up to $3,000 of other income ($1,500 if married filing separately) at your federal bracket plus the state rate. Anything left carries forward to later years.
• Transaction costs are counted twice, once for selling the losing position and once for buying its replacement, and subtracted from the tax savings to get a net benefit.
• Wash-sale risk is flagged from your reinvestment choice: holding cash instead of reinvesting is flagged low risk, and buying a different or similar security is flagged medium. The window is fixed by the rule at 30 days before and after the sale.
• Three harvesting sizes are laid out side by side: a third of your losses, two-thirds, or all of them, each with its own dollar benefit after costs and a low, medium or high risk label.

With a $100,000 portfolio, a 25% federal bracket, a 5% state rate, $10,000 in unrealized losses, no realized gains and $10 in estimated transaction costs, only $3,000 of the loss offsets other income this year. That saves $3,000 x 30% = $900, and the other $7,000 carries forward. Buying and selling costs $20 total, for a net benefit of $880. The harvesting amount is the full $10,000, because costs reduce the benefit, not the loss. The three sized options all net $880 this year: harvesting a third ($3,300), two-thirds ($6,600) or all of the loss gives the same result, since the $3,000 limit is already reached. If you had $10,000 of realized gains to offset instead, the savings would be $10,000 x (15% + 5%) = $2,000, or $1,980 after costs.

• It doesn't distinguish short-term losses from long-term losses, even though the two offset different kinds of gains under actual tax rules.
• Transaction costs are a flat number you enter per trade, not a real bid-ask spread or commission schedule from a specific broker.
• Wash-sale risk here is a simplified flag based on your inputs, not a check against your actual trade history or the securities involved.
• It assumes the tax bracket you entered holds for the whole year; harvesting late in the year against a bracket that's about to change won't be caught. It also does not value the carryforward in later years, and harvesting lowers your cost basis, so it mostly moves tax to a later year rather than removing it.

Finance Quest is educational. It is not financial advice, and no calculator here knows your full situation.

The IRS wash-sale rule disallows the loss if you buy the same or a substantially identical security within 30 days before or after the sale, a 61-day window in total. Selling a fund at a loss and buying it right back a week later to stay invested is exactly the situation the rule exists to catch. If you want to stay in the market while the loss settles, a similar but not identical fund tracking a different index is the usual workaround, which is why the reinvestment choice here affects the risk flag.

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