Year-end tax-loss harvesting checklist (2026)

Key dates

• Thu, Dec 24, 2026 — early close, 1:00 p.m. ET (Christmas Eve). Fri, Dec 25 closed.
• Thu, Dec 31, 2026 — last trading day of 2026. A sale must have a 2026 trade date to count for 2026 (Pub. 550: “Do not confuse the trade date with the settlement date”).
• If you sell on Dec 31, 2026: the look-back starts Tue, Dec 01, 2026 (watch December dividend reinvestments) and the earliest repurchase date is Sun, Jan 31, 2027 — a Sunday, so the first trading day to buy back is Mon, Feb 1, 2027.
• A purchase in January 2027 can disallow a loss realized in December 2026. The window crosses the year boundary.

Checklist

1. List positions with unrealized losses in taxable accounts (gains/losses inside IRAs and 401(k)s don’t count).
2. For each, look up the lot-level cost basis and holding period (short- vs long-term).
3. Check every purchase of the same fund in the 30 days before the planned sale — in all accounts, including IRAs and your spouse’s.
4. Turn off dividend reinvestment and automatic investments for that fund everywhere for the window.
5. Pick a replacement that tracks a different index — use the swap finder.
6. Choose specific-lot identification with your broker if you want to sell particular lots.
7. Place trades early; don’t wait for Dec 31. Leave time for fills and mistakes.
8. Set a reminder for day 31 (our calendar can download an .ics file).
9. Remember the $3,000 ($1,500 MFS) annual limit on net capital losses against ordinary income; excess carries forward (IRC §1211(b), §1212(b)).
10. Keep records and review Form 1099-B in early 2027; brokers generally only flag wash sales for the identical security in the same account.
11. Review the plan with a qualified tax professional before trading.