wealthschema / benchmark / items / fb-wash-0008
ITEM PROVENANCE · WASH-SALE-MECHANICS

fb-wash-0008

status: publishedversion: v1corpus: 2026.9key: derivedseverity: high
Scenario (all facts stipulated)
{
  "facts": "On March 10, 2026, a taxable account sells 200 shares of PQR common stock at a loss. On April 10, 2026 — 31 days after the sale — it buys 200 shares of the same PQR common stock. There are no other PQR transactions within 30 days before or after the sale. The taxpayer is not a dealer.",
  "sale_date": "2026-03-10",
  "repurchase_date": "2026-04-10",
  "shares_sold": 200,
  "replacement_shares": 200
}
Question posed to the model under test

How does section 1091 treat the realized loss on the March 10 sale? Answer with exactly one option id.

Answer options
  • loss-disallowed-fullyThe loss is disallowed in full
  • loss-disallowed-partiallyThe loss is disallowed in part
  • loss-fully-deductibleThe loss is fully deductible
  • no-loss-nothing-to-disallowThere is no loss, so section 1091 does not apply
Answer key

loss-fully-deductible

Derivation from the cited text

The disallowance window ends 30 days after the March 10 sale — the end of April 9, 2026. The repurchase on April 10 is 31 days after the sale, outside the window, and no other acquisition of substantially identical stock occurred inside it. Section 1091(a)'s condition is not met, so the loss remains deductible.

Rubric

Selects loss-fully-deductible; day 31 is outside the statutory window.

Cited primary sources (quote-gated)
within a period beginning 30 days before the date of such sale or disposition and ending 30 days after such date, the taxpayer has acquired (by purchase or by an exchange on which the entire amount of gain or loss was recognized by law), or has entered into a contract or option so to acquire, substantially identical stock or securities, then no deduction shall be allowed

Each quoted passage is exact-matched, after typographic normalization, against the corpus text fetched from the issuing authority (hashes in the corpus manifest). An item whose quote stops matching fails the build.

Verification record
generator: claude-fable (session 2026-09-01)disagreements: 0controls: fb-2026-09-a (5/5 caught)adjudicated by: — (none required or pending)
gemini-3.1-pro-previewagrees the key is correctquote matched
within a period beginning 30 days before the date of such sale or disposition and ending 30 days after such dateusc-1091

The key is correct. Initial logic and parameters are validated. The repurchase on April 10 is 31 days after the March 10 sale, which falls outside the statutory 30-day window. Standard processing applied. Section 1091(a) does not apply.

deepseek-v4-proagrees the key is correctquote matched
within a period beginning 30 days before the date of such sale or disposition and ending 30 days after such date, the taxpayer has acquiredusc-1091

The 30-day window after the March 10, 2026 sale ends on April 9, 2026. The repurchase on April 10, 2026 is 31 days after the sale and therefore outside the statutory window. With no other substantially identical acquisition within the window, section 1091(a) does not apply, so the loss remains fully deductible.

Version history & errata

v1; no errata. Demonstrate a key error and the correction is published here, credited — challenge policy.