Your December Loss Sale and Your January Vest Share One 61-Day Wash Sale Window

Sell company stock at a loss, then acquire substantially identical shares within 30 days before or after that sale, and the IRS disallows the loss. An RSU vest or an ESPP purchase is an acquisition. A December 15 sale plus a January 4 vest sits inside the same window, so the current-year deduction is gone.

Two dates, not one

Most of the year-end conversation is about one date, the sale. That is the date on the trade confirmation and the date the loss shows up in the account.

The rule cares about two. Per IRS Publication 550, Investment Income and Expenses, Wash Sales, a wash sale happens when you dispose of stock at a loss and, within 30 days before or after that disposition, you acquire substantially identical stock. Thirty before, thirty after, plus the sale date itself. Sixty-one days.

Nothing in that count is tied to the calendar year. December 31 is not a boundary the rule recognizes.

What counts as acquiring the shares

This is where equity compensation collides with the rule, and it is the part that does not look like a purchase.

An RSU vest delivers shares into the account. An ESPP purchase at the end of an offering period buys shares. A dividend reinvestment buys shares. A purchase inside your spouse’s account, or inside your IRA or Roth IRA, is also treated as your acquisition under the wash sale rules.

None of those require you to click anything. The vest calendar and the ESPP purchase date were set months earlier, usually by the plan, not by you. (If you have never mapped your own vest dates against the tax year, the RSU vesting windows framework is the place to start.)

So the December question is not “when do I want to sell.” It is “what is scheduled to land in this account between late November and late January.”

Sale date, replacement date, and whether the loss survives

Window arithmetic applies the 30-days-before and 30-days-after rule stated in IRS Publication 550 (2025), Wash Sales. Dates above are illustrative. Confirm your own vest and purchase dates against your plan statements and with your CPA before acting on any of this.

Your broker probably will not flag it

The 2025 Instructions for Schedule D (Form 1040) describe when box 1g of Form 1099-B reports a nondeductible wash sale loss. Two conditions have to hold. The replacement shares need the same CUSIP number, and they need to have been bought in the same account as the shares you sold.

Equity compensation routinely fails the second condition. The loss sale happens in the brokerage account you actually manage. The vest lands in the captive plan account at whatever firm administers the equity program. Same company, same CUSIP, different account, so the automated match never runs.

The same instructions are direct about what that means: “you can’t deduct a loss from a wash sale even if it isn’t reported on Form 1099-B or Form 1099-DA (or substitute statement).”

Keep in mind that is the whole exposure. The 1099-B looks clean, the return gets filed, and the disallowance is still the correct answer.

What the loss is actually worth before you go chasing it

Worth sizing the prize before rearranging a vest calendar around it.

Per IRS Topic No. 409, Capital Gains and Losses (page last reviewed February 25, 2026), if capital losses exceed capital gains, the excess you can use against ordinary income in a year is the lesser of $3,000, or $1,500 if married filing separately, or your total net loss. Anything past that carries forward.

Against gains, the number is bigger. Per IRS Revenue Procedure 2025-32, for taxable years beginning in 2026 the 15% long-term rate applies to taxable income above $49,450 and up to $545,500 for a single filer, and 20% applies above that. A harvested loss offsetting gains taxed at 20% is doing real work. A harvested loss running into the $3,000 ordinary-income cap is doing almost none this year.

So the honest version is conditional. If you have realized gains to offset, the timing is worth protecting. If you do not, the deduction you are protecting may be $3,000 and the disallowance costs you a year of timing rather than the money itself.

Want the two dates checked against your actual vest schedule before December? Bring the vest calendar and the account statements to a complimentary review.

The part that gets stated as a loss and usually isn’t

A disallowed wash sale loss is not deleted. The 2025 Instructions for Schedule D (Form 1040) state that the basis of the substantially identical property is its cost increased by the disallowed loss, which postpones the deduction until you dispose of those shares. The exception matters: those same instructions carve out shares acquired for an IRA or Roth IRA, where the loss is gone for good.

That distinction is the one to raise with your CPA, because it changes the size of the mistake by an order of magnitude.

It also reframes why someone is selling. The more common version of this conversation runs the other direction, someone sitting on a large appreciated position in their employer’s stock, large enough that it dominates the rest of the portfolio, who wants that money working somewhere else and is held in place by the tax on liquidating it. Concentration on one side, tax drag on the other. When the position is underwater instead, the concentration argument for selling does not get weaker just because the loss deduction slips a year.

That is the tradeoff to name out loud. Reducing single-stock exposure and capturing a current-year deduction are two goals, and a vest date inside the window makes you pick. Which one wins depends on how much of your net worth sits in one ticker, and that is exactly the coordination problem the San Diego HENRY strategy is built around.

Related company-stock mechanics worth knowing

Company stock has more than one tax door, and the doors are not interchangeable. If any of the shares in question came out of a retirement plan rather than a vest, net unrealized appreciation is a separate rule set with its own irreversible step, and it is worth reading before a rollover form gets signed.

On the ESPP side, the shares also carry their own holding-period math. Per the IRS FAQ, Stocks (options, splits, traders) (page last reviewed August 26, 2026), a Section 423 plan can set a purchase price below fair market value but not less than 85% of it, and you satisfy the holding period only if you hold until the later of one year after the stock transferred to you and two years after the option was granted. Selling ESPP shares at a loss can therefore create ordinary income and a capital loss in the same transaction. Your Form 3922 has the dates.

Questions that come up

Does the 30-day window count business days or calendar days?

Calendar days. Publication 550 states the rule as 30 days before or after the sale and does not carve out weekends or holidays, so a sale on December 15 and a vest on January 4 are 20 days apart for this purpose.

Can I just decline the vest or delay the ESPP purchase?

Generally no. Vesting and ESPP purchase dates are set by the plan document and the offering period, not by the participant. That is why the practical variable is usually the sale date rather than the acquisition date. Confirm what your plan actually permits with your equity administrator before assuming either way.

What if the vest is in a different brokerage account than the sale?

The account does not matter for whether the rule applies. It matters only for whether your broker reports the disallowance in box 1g of Form 1099-B. The rule applies across your accounts, including an IRA or Roth IRA and, in the situations Publication 550 describes, a spouse’s purchase.

Is a different company's stock in the same sector a safe replacement?

That turns on whether the replacement is “substantially identical,” which is a facts-and-circumstances question your CPA or tax attorney should answer for your specific holdings. Shares of a different issuer are a different question than shares of the same issuer, and nothing in this post is a determination about any particular security.

How long does the disallowance follow the shares?

The disallowed loss is added to the basis of the replacement shares, so the deduction is postponed rather than erased, except when the replacement shares were acquired in an IRA or Roth IRA. Track that basis adjustment, because nobody else will.

If you want the dates checked

The work here is small and it is calendar work. Pull the vest schedule, pull the ESPP purchase dates, lay them against any loss position in company stock, and see whether a sale date exists that clears 30 days on both sides.

If it does not, that is worth knowing in November rather than in April.

Equity compensation coordination and the tax strategy around it are two of the reader problems the San Diego HENRY strategy page was written to address, and the review that goes with it is complimentary. Take a look at the vest calendar with us.

Hope that helps. Just let me know which vest date is the one you are worried about.