The 61-day window behind your loss harvest costs the position, not just the trade. The rule reaches back 30 days before the sale, so a purchase you made last month can void the tax break before your trade even settles. That one date rule turns a simple harvest into a hard choice for anyone holding a large block of employer stock.

The big picture:

Loss harvesting is sold as a simple idea: take the loss, buy something similar, stay in the market.

That works when the replacement is another fund tracking the same index. It fails on a single stock.

The test is whether the new shares are “substantially identical” to the old ones, and the Internal Revenue Service (IRS) says stock of one company is usually not treated as the same as stock of another [5]. Buy a different company and you change the bet. Buy the same company inside the 61-day band and the loss is blocked [1].

What strikes me here is how hard this cuts against the usual story about holding one stock. The tax break matters most to the reader who wants to keep the shares, yet that is exactly who the rule hurts. A holder who already decided to sell collects the tax break for free, since the band costs them nothing they were not already giving up.

By the numbers

  • 61 days — Window length: the band opens 30 days before the sale and closes 30 days after it, and any buy of the same stock inside it blocks the loss [1][2].
  • $3,000 — Slice against salary: losses come off realized gains with no cap at all, but only the remainder can lower other income by up to $3,000, or $1,500 on a separate return [3][4].
  • 20 years — $60,000 with no gains: a loss that size becomes a twenty-year drip of $3,000 a year, and that division is my own sum, not the code’s [3][4].
  • Day 31 — First clean re-buy: the band closes 30 days after the sale, so the first clean buy outside it falls on the day after [1].

What I’d watch:

Nearly all the risk lives in the calendar rather than the tax form, because the band runs backward as well as forward.

  • The purchase before the sale: an automatic buy through an employee stock purchase plan (ESPP) or a broker’s standing order inside the previous 30 days can void a sale that looked clean [1][2].
  • Where a voided loss goes: the loss is put off rather than lost. The new shares take the old shares’ basis, adjusted for the price gap, and the loss counts when that specific lot is sold [6].
  • The half that pays properly: the offset has no dollar cap against realized gains, which is why a holder closing other positions gets far more from a harvest than the $3,000 limit suggests [3].
  • The open question: the rule targets a buy “by purchase or by an exchange upon which the entire amount of gain or loss was recognized”, but it does not say where a share handed over at vesting falls [1].

I would want to read exactly how a plan manager describes vesting before treating the harvest as safe.

The catch

My read is that the honest version of this rule is much narrower than the way it gets sold.

No source here gives a tax rate, so nothing in this piece turns the loss into actual dollars saved, and any figure that did would rest on a guessed bracket. Two more limits are worth naming. The ban has exceptions for a sale made in the seller’s own trade or business, and for a stock dealer acting in the ordinary course [7], though neither helps a salaried engineer.

Whether two holdings count as the same stock is settled by the facts of a case, not by a set definition [5], so a plan that holds shares in a successor company needs its own read.

The part I keep circling is how lopsided it is. The rule is cheap to satisfy for someone selling anyway and costly for someone who wants to stay, and the twenty-year figure above assumes no future gain ever arrives to soak up the loss.

At a glance

  • The Big Shift: a loss harvested on employer stock is blocked when you buy the same shares inside a 61-day band that opens 30 days before the sale, not just after it.
  • Why It Matters: the deduction’s value depends on whether you plan to keep the position or leave it, and only the departing holder collects the loss without paying for the band.
  • What I’d Watch: where the calendar and the cost basis land when a price drop at vest turns into a tax harvest.
  • The look-back: buys made in the 30 days before a sale count, so an automatic plan purchase can void a harvest that looked clean.
  • The basis rule: a voided loss moves into the new lot and is counted when those shares are sold, putting the loss off rather than forfeiting it.
  • The gains offset: losses come off realized gains in full, and only the remainder is capped at $3,000 against other income.
  • The Catch: the rule’s text does not settle how a vesting date counts, and the twenty-year figure above assumes no future gain ever soaks up the loss.

Related reading

Sources

[1] eCFR, 26 CFR § 1.1091-1 — Losses from wash sales of stock or securities (title 26 up to date as of 10/21/2026). https://www.ecfr.gov/current/title-26/section-1.1091-1 [2] Investor.gov (U.S. Securities and Exchange Commission), glossary: Wash Sales. https://www.investor.gov/introduction-investing/investing-basics/glossary/wash-sales [3] Cornell Legal Information Institute, 26 U.S.C. § 1211 — Limitation on capital losses. https://www.law.cornell.edu/uscode/text/26/1211 [4] Internal Revenue Service (IRS), Topic no. 409 — Capital gains and losses. https://www.irs.gov/taxtopics/tc409 [5] Internal Revenue Service (IRS), Publication 550 — Investment Income and Expenses, “Substantially identical”. https://www.irs.gov/publications/p550 [6] Cornell Legal Information Institute, 26 U.S.C. § 1091(d) — Unadjusted basis in case of wash sale of stock. https://www.law.cornell.edu/uscode/text/26/1091 [7] eCFR, 26 CFR § 1.1091-1(a) — the trade-or-business and dealer exceptions to the prohibition. https://www.ecfr.gov/current/title-26/section-1.1091-1