™Stock Market University · Research, Taxes & Investor Operations
Wash-Sale Recordkeeping Checklist
Understand the idea. See the connections.
Build the transaction record needed to review dates, matched shares, adjusted basis and future disposals.
The idea to understand
Create an audit trail linking dates, lots, quantities, accounts, adjusted basis and the authority used for the conclusion.
The explanation
The essentials, explained.
Follow the idea, then work through an example. Pause at the self-check whenever you are ready.
Record the loss sale
Keep the security, sale date, proceeds, original basis, shares or units, tax lot and resulting loss before any wash-sale adjustment.
Record every possible replacement
List acquisitions during the full 61-day window, including automatic reinvestments, options or contracts and activity in other relevant accounts.
Document the adjustment
For affected taxable-account shares, record the matched quantity, disallowed loss allocated to those shares, adjusted replacement basis and carried holding period.
Reconcile before filing
Compare broker forms with your complete transaction history. Preserve statements and calculations, and raise cross-account, spouse, retirement-account or classification questions with a qualified tax professional.
Optional context & practice
Why this matters
A complete tax record can require reconciliation beyond one institution’s form. Quantities, dates and adjustments must remain traceable across lots.
Useful vocabulary
Tax lot: A specific group of shares or units acquired in one transaction, with its own acquisition date and basis. Cost basis: The value used to calculate a taxable gain or loss, generally adjusted for certain transactions and events. Form 1099-B: A US broker information return reporting certain proceeds and, where applicable, basis and related adjustments for securities transactions.
Preserve a calculation someone else can reproduce
A useful record links each disposed lot to dates, quantities, proceeds, basis and matched acquisitions, then shows the adjustment carried to each replacement. Separate taxable-account basis changes from IRA disallowance. Retain the reason for an identity conclusion and the authority used. Calendar screenshots alone are insufficient when actual share matching or cross-account treatment is disputed.
Try it with a hypothetical example
Reconcile trade confirmations, lot records and relevant broker forms. Mark cross-account information the forms may omit and preserve a dated adjustment worksheet.
A question to think through
What evidence would let a reviewer reproduce a partial wash-sale adjustment?
Compare your reasoning
The sale and acquisition confirmations, identified lots, per-share losses, ordered matching, affected account types, replacement-basis changes and any carried holding periods.
A moment to reflect · optional
What makes the record useful years later?
Think through your answer, then compare it with the explanation.
Reveal the explanation
A reproducible calculation showing which shares matched, why, and how basis and holding period were adjusted.
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Sources & editorial notes
Reviewed 2026-10-13 · My Market Book editorial team. Examples are hypothetical unless identified as historical. General education, not a personal investment recommendation. Next scheduled review: 2026-11-12, or earlier after a material change. Rule and product sensitive.