RSU Tax-Loss Harvesting and the Wash Sale Rule

Your company's stock dropped after a vest. You're sitting on a loss and you want to harvest it against other gains. Sounds simple — until you realize that your next RSU vest is in three weeks. That vesting event may just have triggered the wash sale rule and disallowed the entire loss.

For tech employees with regular quarterly vesting schedules, the wash sale rule creates a trap that most tax software and many generalist advisors miss. Here's how it works and what to do about it.

What the wash sale rule actually says

IRC § 1091 disallows a realized loss on a security sale if you acquire a "substantially identical" security within the 61-day window surrounding the sale — that's 30 days before the sale date through 30 days after.¹

The word "acquire" is broader than "buy." It includes open-market purchases, reinvested dividends, stock received through a broker — and, critically for RSU holders, shares received through vesting.

Why RSU vesting counts as an acquisition

When RSUs vest, you receive actual shares of your employer's stock. The IRS and established tax practice treat this as an acquisition of securities for wash sale purposes — functionally equivalent to going into the open market and buying those same shares.²

The shares are identical to any other shares you might sell at a loss. Same ticker, same class, same company. "Substantially identical" is easily satisfied when you're talking about shares of the same company from the same equity class.

This means that for a senior engineer with quarterly RSU vests — March, June, September, December — there are only brief windows each quarter where selling at a loss clearly avoids the 61-day wash sale window. Miss those windows and your loss is disallowed, at least temporarily.

Disallowed losses: deferred, not gone

The good news: a wash sale does not permanently eliminate your loss. Two things happen instead:

• The disallowed loss is added to the cost basis of the replacement shares (the shares you received through vesting). You'll recognize that loss eventually, when you sell the replacement shares.
• The holding period of the original shares is tacked onto the replacement shares. This can accelerate your path to long-term capital gains treatment on the replacement shares.

The catch: "eventually" may be years away, and in the meantime, your other gains this year remain unshielded. If you were trying to offset a $2,000 capital gain with a $2,000 loss, the wash sale means you pay tax on that gain this year and only recover the loss basis when the vested shares are later sold — which might not happen until next year or later.

The quarterly vesting problem, illustrated

Suppose your RSUs vest every March 15, June 15, September 15, and December 15. You want to harvest losses sometime in late October, when your employer's stock has declined. Here's the wash sale calendar for that quarter:

For quarterly vesters, this often leaves a clean window of roughly 6–7 weeks between the end of the 30-day post-vest window and the start of the 30-day pre-next-vest window. Miss that window and the loss is likely disallowed.

The sell-to-cover complication

Most employers default to "sell-to-cover" at vesting: they sell some shares automatically to cover withholding tax, and you receive the net shares. This means you receive fewer shares at vest, but you still received shares. The wash sale window is triggered by the vesting event itself, not by how many shares you retain afterward.

If your employer sells shares on your behalf at vest to cover taxes, and you simultaneously sell additional shares at a loss to harvest it, you may be triggering a wash sale on shares received the same day.

ESPP and the wash sale rule

Employee Stock Purchase Plans (ESPP) add another dimension. If your ESPP purchase date falls within the wash sale window — 30 days before or after a loss sale — the ESPP acquisition can disallow the loss. ESPPs purchase shares at a discount, often at the lower of beginning-period or end-period price, and those shares are "substantially identical" to any other shares you might sell at a loss.³

See our ESPP tax guide for more on how ESPP purchase and disposition timing interacts with broader equity comp tax planning.

Strategies that work

1. Sell in the clean window

Map your vest schedule (and ESPP purchase dates) for the year and identify the 30-day windows on each side of every acquisition date. Only sell at a loss during the periods that fall outside all those windows. For quarterly vesters, there are typically two windows per year where a clean loss harvest is possible — early in Q1 and early in Q3, depending on vest dates.

2. Use a 10b5-1 plan to pre-schedule clean-window sales

If you're an insider subject to trading blackout windows, a 10b5-1 trading plan can be designed to schedule loss-harvesting sales during blackout-adjacent periods — but outside the wash sale windows around vest dates. The plan must be set up during an open window before the trades are needed, which requires advance planning.

3. Sell immediately at vest (no loss basis to harvest)

The simplest way to never trigger a wash sale on RSU shares is to sell them at vest. Since your basis equals the vest-day FMV, an immediate sale produces no gain and no loss — nothing to trigger a wash sale. The tax is on the ordinary income at vest regardless of when you sell. This is our sell-immediately analysis.

4. Replace with a similar-but-not-identical ETF or stock

Classic tax-loss harvesting replaces the sold security with something that tracks the same market exposure without being "substantially identical." For employer stock, this is harder — you can't hold a single-stock position and swap it with itself. But you can sell employer stock at a loss, put the proceeds into a broad tech-sector ETF or S&P 500 fund, and buy back the specific employer stock after 31 days. You maintain market exposure during the 31-day window without triggering the wash sale.

This works if your investment thesis is correlated-sector exposure. It doesn't help if you specifically want continued exposure to your employer's stock.

5. Accept the disallowance and track it carefully

Sometimes the wash sale happens unavoidably — the stock drops hard right before a vest and you want the loss on the books. In that case, sell the loss shares, let the disallowed loss roll into the basis of the replacement vested shares, and track the adjusted basis carefully. The loss will come back when you sell the replacement shares. The cost is timing: you pay tax on offsettable gains now and recover the loss later.

The AMT interaction for ISO holders

If you hold ISOs alongside RSUs, the AMT calculation creates an additional layer. ISO exercise-and-hold positions can generate a tax preference that reduces regular tax in later years — but AMT alternative minimum taxable income is calculated before the wash sale disallowance adjustment. An equity-comp specialist needs to model both simultaneously: wash sale timing, ISO exercise strategy, and AMT exposure often interact in ways that aren't apparent from looking at each in isolation. See our ISO AMT calculator for the underlying mechanics.

What the loss actually costs you (in dollars)

When a wash sale disallows a $10,000 loss that you needed to offset gains this year, the dollar cost is the tax you pay on those gains — deferred, not eliminated. For a single filer at $300K–$450K combined income:

• Long-term capital gain taxed at 15% + 3.8% NIIT = 18.8% effective rate
• A disallowed $10,000 loss costs you $1,880 this year
• You recover it when the replacement shares are eventually sold — but not until then

At higher income levels (above $545,500 single), that LTCG rate climbs to 23.8%, making the timing cost of a wash sale more significant.

Short-term gains are costlier: at a 35% marginal rate, a disallowed $10,000 STCG offset costs you $3,500 this year.

What an advisor does differently

A fee-only advisor who specializes in equity compensation will typically:

• Map your full vest and ESPP calendar at the start of each year and identify clean loss-harvesting windows in advance
• Coordinate loss harvesting with your ISO exercise schedule — both affect the same tax year, and the wash sale analysis depends on the combined picture
• Track adjusted cost basis across your company-plan account and personal brokerage, since cross-account wash sales aren't caught by brokers
• Design 10b5-1 plans (for insiders) with wash sale windows already excluded from the sales schedule
• Model the multi-year tax impact: is it better to take a clean loss this year by delaying a sale, or accept the disallowance and recover it next year?