Tax Research & Documentation

Why this topic matters

Tax Compliance and Planning (TCP) expects candidates to find and weigh tax authority, reach a supportable conclusion, and document it. Research task-based simulations may ask you to identify the correct Internal Revenue Code (IRC) section or authority for an issue. Knowing the hierarchy of authority and the professional standards for positions is essential.

Sources of tax authority

Primary authority — statutory

• The US Constitution (the Sixteenth Amendment authorizes the income tax).
• The Internal Revenue Code (Title 26 of the US Code) — the highest statutory authority after the Constitution.
• Tax treaties — equal in weight to the Code; generally the later-in-time rule resolves conflicts.
• Legislative history — House Ways and Means and Senate Finance Committee reports, and the Joint Committee on Taxation's general explanation ("Blue Book") — helps interpret ambiguous provisions.

Primary authority — administrative

Source	Weight and use
Treasury Regulations — final, temporary, and proposed	Final and temporary regulations carry substantial weight (legislative regulations, issued under a specific delegation, the most). Proposed regulations are not binding but indicate the government's position.
Revenue rulings	The Internal Revenue Service (IRS) position applying the law to specific facts; published and relied on by all taxpayers with similar facts
Revenue procedures	Procedural guidance (how to request a ruling, safe harbors, inflation-adjusted amounts)
Notices and announcements	Timely guidance, often before regulations
Private letter rulings	Binding only for the taxpayer who requested them — no precedential value for others, but they can count as substantial authority and indicate IRS thinking
Technical advice memoranda, chief counsel advice	Issued in specific cases; not precedent

Primary authority — judicial

Court	Precedential weight
US Supreme Court	Binding on all courts and the IRS
US Courts of Appeals (circuit courts)	Binding within their circuit
US Tax Court — regular decisions	Precedent (the Tax Court follows the circuit to which a case is appealable — the Golsen rule)
Tax Court memorandum decisions	Apply settled law to facts; persuasive
Tax Court small case (summary) decisions	No precedential value
US District Courts and the US Court of Federal Claims	Persuasive; binding only in the case

The IRS may issue an acquiescence (it agrees with an adverse decision) or nonacquiescence (it will continue to challenge the issue).

After the Supreme Court's 2024 decision in Loper Bright Enterprises v. Raimondo, courts no longer automatically defer to an agency's reasonable interpretation of an ambiguous statute (the former Chevron doctrine). Courts now decide the best reading of the statute themselves, giving Treasury interpretations respect based on their persuasiveness — which may make some regulations easier to challenge.

Secondary sources

Tax services and treatises, journal articles, newsletters, and citators (which show whether a case or ruling has been followed, distinguished, or overruled). Secondary sources help locate and explain authority but are not authority themselves.

The research process

1. Gather the facts — all relevant facts, and identify any missing ones.
2. Identify the issues — frame specific questions of law.
3. Locate authority — start with the IRC, then regulations, rulings, and cases; use keyword and citation searches.
4. Evaluate authority — relevance, weight, currency (check citators and later law changes, such as the One Big Beautiful Bill Act (OBBBA) of 2025), and whether the facts match.
5. Reach a conclusion — and assess its strength (the confidence level for penalty standards).
6. Communicate — a research memo for the file and a client letter.

Standards for tax positions

Standard	Approximate likelihood of being sustained	Used for
Not frivolous	—	Minimum for any position
Reasonable basis	About 20%	A position that is adequately disclosed (Form 8275)
Substantial authority	About 40%	An undisclosed position — avoids the substantial understatement penalty
More likely than not	Over 50%	Tax shelters and reportable transactions; financial statement recognition of uncertain tax positions

Substantial authority is weighed objectively using primary authorities, private letter rulings, technical advice memoranda, and similar official sources — not treatises or articles.

Documentation

• Research memo (for the file): facts, issues, conclusions, and analysis with citations — supporting the position if challenged.
• Client letter: clear, non-technical explanation of the conclusion, risks, and recommendations — including any penalty exposure and how disclosure could reduce it.
• Keep work papers showing sources consulted and the reasoning.
• Written advice must meet Circular 230 §10.37 standards (reasonable assumptions, all relevant facts, no reliance on the audit lottery), and the American Institute of Certified Public Accountants (AICPA) Statements on Standards for Tax Services.

Citation formats (examples)

• Code: IRC §162(a) — Section 162, subsection (a).
• Regulation: Treas. Reg. §1.162-5 — the "1" denotes income tax regulations under Code Section 162.
• Revenue ruling: Rev. Rul. 2020-1, 2020-2 I.R.B. 1 (year and ruling number; then Internal Revenue Bulletin volume and page).
• Tax Court: Taxpayer v. Commissioner, 150 T.C. 1 (2018).

How it is tested

• Rank sources by authority and precedential value.
• Identify which authorities count for substantial authority.
• Match a position to the standard needed with and without disclosure.
• Locate the correct Code section or authority for an issue.