Constructive Sale Rule Considerations US

When to Use

Use this skill when managing US taxable portfolios, tax-loss harvesting algorithms, or hedging strategies against appreciated long positions. Under 26 U.S.C. § 1259, entering into certain offsetting transactions against an appreciated financial position triggers an immediate constructive sale: gain is recognized as if the position were sold at fair market value on the date the offsetting transaction is entered into, even though the long position is still held.

Only four transaction categories are constructive sales by operation of the statute (§ 1259(c)(1)(A)–(D)):

When NOT to Use

• Options-based structures. Collars, in-the-money puts, and similar transactions are not listed in § 1259(c)(1)(A)–(D). They can reach § 1259 only through § 1259(c)(1)(E), which applies "to the extent prescribed by the Secretary in regulations" — and Treasury has never issued those regulations. The engine returns MANUAL_REVIEW_REQUIRED for these; do not let an agent auto-classify them.
• Marked-to-market positions. § 1259(b)(2)(C) excludes positions already marked to market (§ 1256 contracts, securities held under a § 475(f) election) from the definition of an appreciated financial position.
• Non-US taxpayers or non-US tax regimes. This skill encodes US federal income tax only.
• As a substitute for tax advice. The engine is a deterministic audit aid; a qualified US tax adviser owns the filing position.

Prerequisites

• Python 3.10+ and the standard library only (datetime, dataclasses, typing, math, logging).
• Long position cost basis and fair market value as of the offsetting transaction's entry date (§ 1259(a)(1) measures gain at that date, not at the reporting date).
• Entry date, close date, and the end of the taxable year in which the transaction was entered into (not always Dec 31 — fiscal-year filers supply their own).
• Any disposal of the long position, and any § 246(c)(4) risk-reduction events, in the 60 days after the close.

Workflow

1. Appreciated position gate (§ 1259(b)): If the position is marked to market, or FMV ≤ cost basis, exit with NOT_APPLICABLE. § 1259 reaches only positions that would produce gain on a sale.
2. Per se trigger classification (§ 1259(c)(1)): Map the offsetting transaction to (A)–(D). If it does not map — a collar, an ITM put, a variable prepaid forward with non-fixed quantity — return MANUAL_REVIEW_REQUIRED and escalate. Do not infer a trigger from § 1259(c)(1)(E) while no regulations exist under it.
3. Scope the constructive sale: A partial hedge constructively sells only the hedged portion. Supply offsetting_quantity so gain is pro-rated rather than recognizing the entire lot.
4. Safe harbor test A — 30-day close (§ 1259(c)(3)(A)(i)): The transaction must be closed on or before the 30th day after the close of that taxable year. For a Dec 31 year end that is Jan 30; for a Jun 30 year end it is Jul 30. Not closed, or closed later ⟹ CONSTRUCTIVE_SALE_TRIGGERED.
5. Safe harbor test B — 60-day holding (§ 1259(c)(3)(A)(ii)): The taxpayer must hold the appreciated position throughout the 60-day period beginning on the close date (close date is day 1, so the period ends on close + 59 days). Disposal inside that period ⟹ triggered.
6. Safe harbor test C — 60-day unhedged (§ 1259(c)(3)(A)(iii) via § 246(c)(4)): No risk-of-loss reduction at any time in that period — no option to sell, no contractual obligation to sell, no open short in substantially identical property, no written call.
7. Apply the (c)(3)(B) carve-out before concluding: A risk-reducing transaction entered inside the 60-day window is itself disregarded if it is closed by the 30th day after the close of the first transaction's taxable year and it independently satisfies clauses (ii) and (iii). Re-hedging inside the window is therefore not automatically fatal — check (c)(3)(B) first. Chained re-hedges are not clearly covered by the statute and return MANUAL_REVIEW_REQUIRED.
8. Emit the § 1259(a) consequences: On a trigger, recognize FMV(entry_date) − basis on the hedged quantity, set the new basis to that FMV (§ 1259(a)(2)(A)) and restart the holding period on the constructive sale date (§ 1259(a)(2)(B)).

Full procedure: see references/workflows.md. Statutory citations: see references/standards.md. Printable pre-flight checklist: see assets/checklist.md.

Common Pitfalls

• Treating an ITM put or collar as a per se trigger. § 1259(c)(1) does not list options. Congress left them to regulations under (c)(1)(E) that have never been issued. Auto-recognizing gain here overstates the taxpayer's liability on a position the statute does not reach.
• Valuing the gain at the reporting date. § 1259(a)(1) fixes FMV on the constructive sale date — the date the offsetting transaction was entered into. Feeding today's FMV into a December trigger produces a wrong number in both directions. Pass valuation_date so the engine rejects a mis-dated price instead of silently using it.
• Confusing the two rules about puts. Buying a protective put is not itself a constructive sale, but holding one does reduce risk of loss under § 246(c)(4)(A) — so it breaks the § 1259(c)(3)(A)(iii) safe harbor for a different, already-closed short. The two questions have different answers.
• Assuming re-hedging inside the 60 days is always fatal. § 1259(c)(3)(B) can disregard the second transaction if it is closed by the same 30-day deadline and stands clean on its own 60-day test.
• Forgetting the holding requirement. § 1259(c)(3)(A)(ii) requires holding the long throughout the 60 days. Closing the short in time and then selling the stock 20 days later loses the safe harbor even though nothing was re-hedged.
• Hard-coding Jan 30. The deadline is 30 days after the taxpayer's year end. Fiscal-year entities have a different date.
• Ignoring the related-person rule. § 1259(c)(1) applies when "the taxpayer (or a related person)" enters into the transaction. Hedging in a second entity or a spouse's account does not avoid the rule; this engine evaluates one account at a time, so aggregate across related accounts before calling it.
• Applying it to positions held at a loss. § 1259 reaches only appreciated financial positions (FMV > cost basis).

Verification

• Instantiate ConstructiveSaleRuleEngine. Test an appreciated long ($100k basis, $250k FMV) hedged by a short entered Dec 1, 2025 and closed Jan 15, 2026, held clean for 60 days ⟹ SAFE_HARBOR_QUALIFIED. Change the close to Jan 31, 2026 ⟹ CONSTRUCTIVE_SALE_TRIGGERED with $150,000 gain, adjusted basis $250/share, and holding period restarting Dec 1, 2025.
• Confirm an ITM_PUT offsetting transaction returns MANUAL_REVIEW_REQUIRED, not a trigger.
• Run the suite:

python -m unittest discover -s skills/constructive-sale-rule-considerations-us/scripts

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