Get the official text of an Internal Revenue Code provision.

Args: citation: Any citation form, e.g. "162", "§ 162(a)", "I.R.C. § 7701(a)(30)(A)". include_children: Include the text of every subdivision below it. max_chars: Truncate the text at this length. as_of: Read the law as it stood on this date (YYYY-MM-DD). Tax questions are usually about a past year, and current law is often the wrong answer.

Get the official text of a Treasury Regulation.

Args: citation: Any citation form, e.g. "1.162-1", "Treas. Reg. § 1.263(a)-4(b)(1)". include_children: Include the text of every paragraph below it. max_chars: Truncate the text at this length.

Search the text of the Code and the regulations.

Args: query: Words or a phrase to look for, e.g. "ordinary and necessary". source: "irc", "reg", or "all". limit: Maximum number of results.

Parse a citation and say whether the provision it names actually exists.

Args: citation: The citation to check, e.g. "§ 162(z)".

Look up a court decision, and check a passage you mean to quote from it.

Use this before you attribute language to a case. A citation that resolves is not evidence that the words you put in quotation marks are in it, and a quotation that is nearly right is the failure this catches.

Args: citation: The case, e.g. "Welch v. Helvering, 290 U.S. 111 (1933)". quote: A passage to check against the decision. Give the words only; enough of them to be distinctive — a handful is not enough to be sure of.

Check every citation and quotation in a draft against the official sources.

Run this on your own draft before you finish, and fix every error-severity finding.

Args: text: The draft to check, as Markdown or plain text. tax_year: Also flag any provision that did not govern this tax year. Pass it whenever the question is about a particular year, which in tax it usually is.

List what a provision cites, and what cites it.

Args: citation: The provision to look at, e.g. "§ 1411". direction: "outgoing", "incoming", or "both".

Find where a term is defined, and what scope the definition has.

Args: term: The term to look up, e.g. "gross income". limit: Maximum number of definitions to return.

Classify a draft's citations as authority, or not, for penalty purposes.

Applies Treas. Reg. § 1.6662-4(d)(3)(iii), which lists what counts as authority for the substantial-authority standard under I.R.C. § 6662. Treatises, law review articles and practitioners' opinions are expressly not authority; a position resting on them has a penalty-protection problem. This classifies; it does not weigh.

Args: text: The draft to analyse. tax_year: Also check each authority against this tax year.

Show how a provision changed between two dates.

Args: citation: The provision, e.g. "§ 163(j)". from_date: The earlier date, YYYY-MM-DD. to_date: The later date; current law if omitted.

List everything you must read to understand a provision.

Tax provisions are a graph. Before asserting what § 163(j)(1) means, read what it points at. This walks outward, nearest first.

Args: citation: The provision to start from, e.g. "§ 163(j)". depth: How many hops to follow. The transitive closure of the Code is the Code. limit: Maximum number of provisions to return.

List a provision's subdivisions, so you can fetch the one you need.

Args: citation: The provision to open up, e.g. "§ 163".