Figures: tax year 2026
Substantiation establishes the facts supporting a return item, including its amount, timing, ownership, and any required business connection. Disclosure communicates a return position and its relevant facts to the Internal Revenue Service (IRS) through the prescribed filing method.
- Payment evidence establishes that money changed hands; invoices, agreements, and activity records explain what the taxpayer purchased and why.
- The governing deduction rule determines whether the expenditure qualifies and whether special documentation must exist by a particular deadline.
- Disclosure can affect specified penalty consequences, but it cannot establish missing facts or create substantive entitlement to a deduction.
A reviewer must identify whether substantiation establishes each necessary element before accepting the amount entered on the return.
Different deductions impose different documentation requirements.
The Cohan rule permits a court to estimate certain deductible expenses after credible evidence establishes that an expense occurred and provides a reasonable estimation basis. The court need not accept the claimed total and may resolve uncertainty against the taxpayer.
Common mistakes
- Payment proves every element. A canceled payment establishes cost but may leave ownership, timing, or business purpose unresolved.
- Small gifts need no records. An undocumented $40 monetary gift fails the mandatory written-record requirement.
- Every meal is strict travel. Determine whether the meal is part of qualifying travel before assigning the strict travel substantiation rules.
Bottom line
- Substantiation proves the facts of a return item; disclosure communicates its treatment and potential controversy.
- Cohan estimation requires credible evidence and a reasonable estimation basis, and cannot replace mandatory documentation.
- Monetary charitable gifts require written evidence; acknowledgment, noncash reporting, and appraisal rules impose additional requirements.
- Ordinary substantial-understatement relief can depend on substantial authority or reasonable basis with adequate disclosure, subject to the applicable conditions.
Exam shortcut
Identify the requested conclusion first: factual support, additional position disclosure, mandatory transaction reporting, or foreign-account reporting. For records, classify the expense before judging the documents. Mark the missing element and distinguish a replacement record from an unsupported estimate. For disclosure, screen reportable transactions independently. Then locate any Treasury regulation conflict and check whether ordinary return disclosure is expressly permitted.
The full lesson (about 6,002 words, 40 min read) adds 4 worked examples, all 6 common mistakes, a self-check, free in the app.
Learning objectives
- I.C2
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