Every figure tied out to the authority it came from.
TaxCite reads the Internal Revenue Code, the Treasury Regulations, the Bulletin and federal case law. It checks what a draft cites, finds what governs a question, and computes what follows — and it tells you what it could not check.
Not a recommendation. It applies a rule to figures you supply, names the ruling the rate came from, and lists what it did not determine.
Three failures that read identically on the page
A fabricated citation, a misquoted statute and a correct quotation hung on the wrong section all look like confident prose. They need completely different corrections, so each is reported as a different thing.
“the standard set up by the statute is not a rule of law; it is rather a way of life.”
Welch v. Helvering, 290 U.S. 111. Every word occurs in the decision, in order.
“… it is rather a way of life a submarine protocol.”
Misquoted, not invented. The first seventeen words are genuine; it stops matching at “submarine”.
“quarterly submarine inspection protocols govern the deduction of periscope costs.”
No run of these words occurs anywhere in the decision it was attributed to.
It returns a report, not a verdict
Markdown for a reader, JSON for a pipeline, GitHub annotations for CI. Every finding carries the provision it matched, a word‑level diff, and a link to the official text.
1 I.R.C. § 162(a) ok: verified, quote_exact 2 I.R.C. § 162(z) ERROR: pinpoint_not_found ↳ § 162 has subsections (a)–(s); there is no (z) 3 I.R.C. § 263(a) ERROR: quote_misattributed ↳ the quoted language appears at I.R.C. § 61(a) 4 Rev. Rul. 82-204 warning: superseded ↳ Rev. Rul. 2026-3 states that it supersedes this 5 T.C. Memo. 2099-999 ERROR: not_found ↳ dated 2099, which is in the future 6 Smith v. Jones, 9 T.C. 1 info: unverifiable ↳ Tax Court coverage is partial — not evidence it does not exist
A sentence that is mostly defined terms
Some regulations cannot be read straight through. A sentence of the consolidated return rules is built out of terms of art, each defined somewhere else.
Terms of art used here, and where they are defined SRLY Treas. Reg. § 1.1502-1(f)(1) member Treas. Reg. § 1.1502-1(b) group Treas. Reg. § 1.1502-1(a) consolidated group Treas. Reg. § 1.1502-1(h) separate return year Treas. Reg. § 1.1502-1(e) What this provision sends you to Treas. Reg. § 1.1502-1(f) — Separate return limitation year I.R.C. § 172 — Net operating loss deduction I.R.C. § 1503(d) — Dual consolidated loss
Nothing here is curated. The cross‑references come from the reference graph and the terms from the definitions index, both built from the official text. Building it exposed a real gap: the eCFR italicises a defined term rather than quoting it, and italics do not survive text extraction — so the most heavily defined corpus in Title 26 had almost none of its own terms indexed.
What a target’s losses are actually worth
One question asked in three parts. Each part is arithmetic or enumeration, and each is traceable to the statute.
§ 381(c) — what carries over
A closed enumerated list of 23 attributes, plus 3 repealed. Read out of the indexed Code, so it cannot drift from the statute. It does not decide whether your transaction qualifies under § 381(a).
§ 382(g) — did a change happen
Each five‑percent shareholder measured against their own low point over three years, increases summed, decreases floored at zero. A seller does not offset a buyer — which is why ordinary trading accumulates toward a change nobody intended.
§ 382(b) — what the ceiling is
Value times the long‑term tax‑exempt rate. That rate is not in the Code: it is published monthly in the Bulletin, and TaxCite reads it from there.
Ownership change on 2026-03-15 — cumulative owner shift 52.00%, over the 50-point threshold of I.R.C. § 382(g)(1). Shareholder Low in window Now Increase Fund A 10.00% 40.00% 30.00% Fund B 5.00% 27.00% 22.00% Founder 18.00% 18.00% 0.00% --------- 52.00% Not applied: attribution under § 382(l)(3); public-group segregation under Treas. Reg. § 1.382-2T(j); options treated as exercised.
What it reads
Official, public‑domain government sources only. No proprietary research service is ever scraped, queried, or depended upon.
26 U.S.C.
Internal Revenue Code. Full Title 26 USLM XML from the Office of the Law Revision Counsel, parsed to the subdivision.
26 C.F.R.
Treasury Regulations. Fetched per section from the eCFR and cached, with paragraph hierarchy resolved.
I.R.B.
IRS guidance. Rulings, Procedures and Notices, plus a citator built from the relations the Bulletin itself states.
Case law
Federal decisions through CourtListener, with case names and quoted passages both checked.
§ 1.6662-4
Authority classification. Sorts what you cited into the closed list that counts for the substantial‑authority standard.
§ 382(f)
Published rates. Read from Table 3 of the monthly applicable‑federal‑rate ruling, in the Bulletin.
What it will not tell you
The limits are the product. A tool that hedges everything is useless, and one that overclaims is dangerous — so each boundary below is stated in the report itself, not only here.
- Whether you are right
- It will confirm that a provision exists and is quoted correctly inside an argument that is completely wrong. It has no view on whether an authority supports the proposition it is cited for.
- Whether a deal works
- The models apply a rule to facts you supply. They do not determine whether an ownership change occurred, whether a transaction qualifies under § 381(a), what a corporation is worth, or whether any of it is advisable.
- Whether a case is good law
- Reversal and abrogation are editorial products, and no free source publishes them. The tempting heuristic was measured and rejected: searching citing opinions for “overruled” returns 119 results for Gregory v. Helvering, which has never been overruled.
- That something is missing
- “Not found” is reserved for sources known to be complete. Tax Court coverage is partial, so a Tax Court citation that misses is reported unverifiable — a miss is not evidence.
- Anything a professional reviewed
- No part of this project has been audited by a licensed tax practitioner. Treat every capability described here as demonstrated on worked examples, not as a benchmarked result.
Your draft stays on your machine
With one exception, spelled out plainly because it matters under I.R.C. § 7216 and the ordinary duty of confidentiality.
The Code and the regulations are held locally, so a quotation from either is checked without a request leaving your computer. Court opinions are not published as a bulk download, so checking a quotation against one means asking whether those words occur in that case — which means sending the words.
What is sent is the quoted passage and the reporter citation. What is not sent is your surrounding text, your file, or your client’s name. --no-case-quotes declines it without going offline; --offline seals the process irreversibly against every outbound request. Read the full privacy statement.
Install
Python 3.11 or newer. The index builds in about ten seconds from an eight‑megabyte download.
$ git clone https://github.com/rakib-nyc/taxcite.git $ cd taxcite && uv sync --all-extras $ uv run taxcite build-index # check a draft, then navigate and compute $ uv run taxcite verify examples/sample_memo.md $ uv run taxcite reading-list "Treas. Reg. § 1.1502-21(c)" $ uv run taxcite carryover $ uv run taxcite owner-shift register.csv # or give the sixteen tools to an assistant over MCP $ claude mcp add taxcite -- uv --directory /path/to/taxcite run taxcite serve
Experimental research software
TaxCite is not tax advice, not legal advice, and not a substitute for professional judgment or a commercial tax service.
It verifies that cited provisions exist, that quoted language matches the official source, and computes figures from rules applied to facts you supply. It does not judge whether a legal conclusion is correct, whether an authority is on point, whether a decision is still good law, or whether a transaction qualifies for any treatment.
No warranty is given. Provided “AS IS”, without warranty or condition of any kind, express or implied, and without any guarantee of accuracy, completeness, currency or fitness for a particular purpose — see sections 7 and 8 of the Apache License 2.0.
You are responsible for independently verifying every authority and every figure you rely on. Do not file, serve or submit work on the strength of this tool alone.
Not affiliated with any government agency. TaxCite is an independent open‑source project. It is not produced, endorsed, certified or reviewed by the Internal Revenue Service, the Department of the Treasury, the Office of the Law Revision Counsel, the Government Publishing Office, or any court. It is not an official form, publication or record, and nothing it produces is one. The statutory, regulatory and judicial texts it retrieves are public‑domain works of the United States government (17 U.S.C. § 105); their use here implies no endorsement.