Wash Sale
Category: Investment
A rule that disallows a loss when you buy substantially identical securities within 30 days before or after the sale. The disallowed loss is added to the basis of the replacement shares.
How Wash Sale fits 2026 planning
Wash Sale sits inside capital gains, dividends, wash-sale timing, and surtaxes such as NIIT that sit beside ordinary brackets. For tax year 2026, US Tax Tools treats year-scoped constants (brackets, contribution limits, wage bases, credit schedules) as separate datasets — so explanations of Wash Sale should be read with the same year selected in any linked calculator.
Category focus: Investment. Readers usually land on this page while comparing a paycheck estimate, a credit phaseout, or a retirement contribution room figure that depends on understanding Wash Sale first.
Worked example
Selling a stock at a $1,500 loss and repurchasing it 10 days later means the loss is deferred into the new shares’ basis.
Treat the example as a teaching sketch, not a filing position. Change filing status, state residency, or mid-year events and the same definition of Wash Sale can produce a different cash outcome even when the glossary text stays the same.
What to watch for
Definitions of Wash Sale can differ slightly across IRS publications, SSA rules, Marketplace subsidy worksheets, and state agencies. When two programs both say “income,” confirm which modification rules apply — MAGI for one credit is not always MAGI for another.
Legislation and inflation adjustments can move the dollar thresholds around Wash Sale without renaming the concept. Prefer the effective date on the primary source (Rev. Proc., SSA notice, USDA table, or state DOR bulletin) over any blog summary — including this one if a later notice supersedes it.
Confirm how Wash Sale appears on your forms by reading the IRS instructions for the schedules that match your facts. Educational definitions here cannot capture every exception or state overlay.
Next step
When you are ready to model numbers, open the Wash Sale related calculator on US Tax Tools. Engines keep tax-year datasets separate so a 2025 habit does not silently reuse a 2026 constant.
Related reading: Tax insights for longer 2026 explainers, Methodology for how engines store cents and traces, and Disclaimer for educational-use limits.