By Joe Wallin | April 2026 | ~6 min read
Updated August 10, 2026, to reflect the long-term gain and loss mechanics of ESSB 6346 §302 as enacted. The bottom line — loss harvesting is a powerful Washington planning tool — stands, but the mechanism runs through the capital gains tax, not through federal AGI directly, and that changes what harvesting can and cannot do.
Washington's new 9.9% income tax has a hard threshold: a $1 million standard deduction against Washington taxable income. Below that line, you owe nothing; above it, 9.9% on every dollar. But "Washington taxable income" is not simply federal AGI — §302 of ESSB 6346 strips out long-term capital gains and losses, then adds back the gains Washington taxes under its capital gains tax (chapter 82.87 RCW). That pipeline, traced in full here, determines exactly how loss harvesting works against this tax.
Harvesting — strategically realizing investment losses to offset gains — remains one of the most valuable tools for Washington residents. But it works through one specific channel, and knowing the channel is the difference between a plan that works and one that doesn't.
This post is part of our Complete Guide to Washington's New Income Tax.
Why the Threshold Changes Everything
In the federal tax system, loss harvesting saves you money at your marginal rate — but the savings are incremental. Reducing your taxable income by $100,000 at the federal level saves you $37,000 if you're in the top bracket. Meaningful, but not transformative.
In Washington's system, loss harvesting can do something the federal system cannot: when your income above the threshold is driven by long-term capital gains, it can eliminate your Washington tax for the year entirely. The savings are not just marginal — they can be total. But the mechanism matters.
Under §302, long-term gains and losses are neutralized out of federal AGI; what enters your Washington base is the add-back of your chapter 82.87 taxable gain. Harvested long-term losses reduce your federal net long-term gain, which reduces the gain Washington taxes under chapter 82.87, which shrinks the add-back — effectively dollar-for-dollar for gains above the capital gains standard deduction. And §302(3) contains a cliff: the add-back applies only in years you actually owe capital gains tax. Harvest enough to owe none, and the add-back — including the standard deduction component — disappears entirely.
Consider a Washington resident in 2028 with $800,000 of wages and a $500,000 long-term gain. Without harvesting: the capital gains tax is $15,540 (7% on $222,000 after the deduction), the income tax base is $1.3 million, and after the §205 credit the total Washington bill is $29,700. Now harvest $250,000 of long-term losses: net gain falls to $250,000 — below the capital gains standard deduction — so no capital gains tax is owed, §302(3) never applies, nothing is added back, and Washington base income is just the $800,000 of wages. Total Washington tax: zero. The harvest saved $29,700 of Washington tax plus federal tax on the netted gains.
The contrast case defines the limit: the same resident with $1.3 million of pure wages gets nothing from harvesting $300,000 of long-term losses. §302(2) adds long-term losses back — they cannot shelter ordinary income in Washington, not even the $3,000 the federal system allows.
That is a powerful incentive to actively manage your realized gains and losses each year.
How Tax Loss Harvesting Works
The concept is simple: sell investments that are currently trading below your cost basis, realize the loss, and use that loss to offset gains or reduce your taxable income.
Under federal tax rules, capital losses first offset capital gains (short-term losses against short-term gains, then long-term losses against long-term gains, then any remaining net losses cross over). If your net capital losses exceed your capital gains, you can deduct up to $3,000 per year against ordinary income. Unused losses carry forward to future years indefinitely.
Washington's income tax starts with federal AGI — but §302 then removes long-term gains and losses and adds back Washington-taxed capital gains, so long-term losses reach the Washington base only through the chapter 82.87 computation, by shrinking the taxed gain. Short-term losses are different: §302 doesn't touch short-term items, so short-term losses that offset short-term gains in federal AGI reduce the Washington base directly. Neither kind needs to be "Washington-specific" — federal netting does the work.
The Wash Sale Rule
The federal wash sale rule (IRC Section 1091) prohibits you from claiming a loss if you purchase a "substantially identical" security within 30 days before or after the sale. If you trigger the wash sale rule, the loss is disallowed and added to the basis of the replacement security.
This means you cannot simply sell a stock at a loss and immediately buy it back. You must either wait 31 days before repurchasing the same security, or purchase a similar but not "substantially identical" investment to maintain your market exposure during the waiting period.
For publicly traded stocks, "substantially identical" is generally interpreted narrowly — shares of the same company are substantially identical, but shares of a different company in the same industry (or a broad index fund versus individual stocks) are generally not.
Note on crypto: As of early 2026, cryptocurrency is not subject to the wash sale rule under federal law. You can sell crypto at a loss and immediately repurchase the same asset. However, Congress has repeatedly discussed extending the wash sale rule to digital assets, and this could change. Check the current rules before executing this strategy with crypto. For more on crypto and Washington's tax, see Crypto and Digital Assets Under Washington's 9.9% Income Tax.
Strategies for Washington Residents
Year-End Threshold Management
The most powerful application of loss harvesting for Washington residents is threshold management. As the end of each tax year approaches, project your AGI. If you are above — or close to — $1 million, identify investments with unrealized losses that can be sold to bring your AGI below the line.
This requires a disciplined approach. Starting in October or November each year, review your portfolio for loss harvesting candidates, estimate your remaining income for the year (including any expected bonuses, K-1 income, or capital gains distributions from mutual funds), calculate how much in losses you need to realize to stay at or below $1 million, and execute the trades before December 31.
The payoff can be enormous. Every dollar of Washington-taxed gain you offset with a long-term loss removes a dollar from the income tax base — 9.9 cents saved — and clearing the capital gains tax entirely triggers the §302(3) cliff, removing the standard-deduction add-back too. The savings stack on top of whatever federal benefit the loss generates.
Gain-Loss Matching Throughout the Year
Don't wait until December. If you realize a significant gain during the year — from selling a business, exercising stock options, or a large liquidity event — look for offsetting losses immediately. The longer you wait, the more market risk you take on: investments that are currently underwater may recover before year-end, reducing your available losses.
This is particularly relevant for founders and executives who have concentrated stock positions. If you are selling company stock (after an IPO, for example) and generating large gains, simultaneously harvesting losses in other parts of your portfolio offsets those gains dollar-for-dollar federally — and, for long-term gains Washington taxes, effectively dollar-for-dollar against the Washington base as well, through the reduced chapter 82.87 add-back.
Building a Loss Harvesting Portfolio
Some advisors construct portfolios specifically designed to generate harvestable losses. The approach typically involves holding diversified, tax-efficient investments as a core portfolio, investing a portion of the portfolio in individual securities or sector funds where volatility creates periodic loss-harvesting opportunities, and systematically harvesting losses and replacing sold positions with similar (but not substantially identical) investments.
Over time, this approach can generate a steady supply of losses to offset gains and manage AGI — essentially creating a "tax alpha" that complements investment returns.
Coordinating with Other Income
Loss harvesting is most effective when coordinated with your full income picture. If you have control over the timing of other income — such as Roth conversions, the exercise of stock options, business distributions, or the sale of property — coordinate those events with your available losses.
One critical caveat: exercising ISOs or NSOs generates ordinary income — and long-term capital losses cannot offset ordinary income in the Washington base, because §302(2) reverses them out. If an exercise will push you over the threshold, harvesting won't neutralize it; manage exercise timing instead. The stock options and RSUs post covers how equity compensation income flows into Washington's tax base.
The Carry-Forward Advantage
Capital losses that exceed your current-year gains (beyond the $3,000 ordinary income offset) carry forward indefinitely under federal law. This carry-forward is valuable in its own right — but it is especially valuable for Washington residents because it gives you a bank of losses to deploy in future high-income years.
Suppose a future year brings a $700,000 long-term gain on top of $1.3 million of other income. Deploying $500,000 of loss carry-forwards cuts the net gain to $200,000 — below the capital gains standard deduction — so no capital gains tax is owed and, under the §302(3) cliff, no gain is added back to the income tax base at all. The carry-forward bank converts a $700,000 add-back into zero. (Against a year of purely ordinary income, the same carry-forwards do nothing in Washington — they only work against gains.)
Building and maintaining a loss carry-forward balance is an underappreciated component of long-term Washington tax planning.
Limitations and Considerations
You need losses to harvest. In a sustained bull market, your portfolio may not have significant unrealized losses. Loss harvesting is opportunistic — it works best when markets are volatile or declining.
Losses cannot shelter ordinary income — at all. If your Washington base income is driven by salary, bonuses, option exercises, or pass-through income rather than capital gains, long-term loss harvesting does nothing against this tax: §302(2) adds long-term losses back, and even the federal $3,000 allowance against ordinary income is reversed out when the losses are long-term. Harvesting is a gains tool in Washington. If ordinary income is your problem, the levers are timing, the PTE election, and the strategies in the Before 2028 guide.
Basis erosion. When you harvest a loss and reinvest in a similar (but not identical) asset, your new basis is lower. If the replacement investment appreciates, you will have a larger gain when you eventually sell it. Loss harvesting doesn't eliminate tax — it defers it. But deferral has real value, especially if you can defer until a year when your AGI is below $1 million.
The PTE election may be more impactful for some. If your income above $1 million is primarily pass-through business income, the PTE election does not change the 9.9% Washington rate, but the entity-level payment is deductible federally outside the SALT cap — for an owner at the top federal marginal rate that brings the net cost to roughly 6.2%, with less complexity than active loss harvesting. Both strategies can be used together, but prioritize the PTE election if you qualify.
Consult your advisor. Loss harvesting interacts with federal tax rules, state tax rules, portfolio strategy, and your overall financial plan. It should be implemented as part of a coordinated approach, not in isolation.
What to Do Now
If you are a Washington resident with a taxable investment portfolio and an AGI near or above $1 million, loss harvesting should become a routine part of your annual tax planning. Start by reviewing your portfolio for unrealized losses today. Not because the tax takes effect today — but because building the habit and infrastructure now means you will be ready to execute when January 1, 2028 arrives.
For more on managing Washington's income tax, see our Washington State Taxes guide and Tax Planning Guide for High Earners. If you hold crypto or digital assets, note that the wash sale rule does not currently apply to cryptocurrency — see Crypto and Digital Assets Under Washington's 9.9% Income Tax for how this expands your loss harvesting options.
This post is for informational purposes only and does not constitute legal or tax advice. Consult with a qualified tax professional regarding your specific circumstances.
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