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ecfr-title-26

reference corpus · status live · domain LAW (Law and regulation) · lane A · refresh pinned · tags US · TAX · LAW · STANDARDS · IRS · INTERNAL-REVENUE

What an agent uses it for

an agent answering federal tax questions queries this for what the Treasury regulations actually say: de minimis safe harbor, estimated-tax safe harbor, home-office exclusive use (demand: tax Ask-HN volume 40)

Use it
curl -fsSLO https://raw.githubusercontent.com/xerj-org/xerj/corpus-hub/tools/xerj-code/hub/ecfr-title-26.json
xerj corpus add --from ./ecfr-title-26.json
xerj corpus index ecfr-title-26 then xerj code ecfr-title-26 "your question"

Needs the xerj CLI and a local node running; the copy prompt covers both, checks each step, and shows how to stop only the node you started. No shell: the MCP tool xerj_code_search with corpus: "ecfr-title-26", once the corpus is indexed on the node.

Sources and pins

sourcepinlicencesizereview note
ecfr-title-26 3f3e58c72cbcUS-government-public-domain 70.7 MB / 6,202 files eCFR Title 26 (IRS) current consolidated regulation, section-per-file; US government work, no copyright (17 USC 105). G7 3/5 relevant 2026-10-05, dupcheck 49682 docs CLEAN.

70.7 MB across 6,202 files. Added 2026-10-05.

People behind this corpus

Upstream authors (1)

Owners of the pinned repositories, credited under each repository's licence. They have not signed up here; their pages are attribution.

xerj-org@xerj-org · upstream

All contributors.

Rights

US-government-public-domain. Redistribution permitted with attribution per the licence review. The review block records a human opening each licence file at the pin. Detector output is a hint, never the verdict.

Retrieval spot-check (G7)

1.0/5 relevant. Graded 2026-10-02T22:25:00Z.

Q: What is the de minimis safe harbor amount for expensing tangible property without an applicable financial statement?
expect: 26 CFR 1.263(a)-1(f): $5,000 per item/invoice with AFS, $2,500 without
top-5: part-1/sec-1.162-3 / part-1/sec-1.263(a)-1 / part-1/sec-1.263(a)-0 / part-1/sec-1.162-3 / part-1/sec-1.263(a)-1
grade: relevant
Q: What prior-year safe harbor avoids the estimated tax underpayment penalty?
expect: 26 CFR 1.6654-2(d): 100% of prior-year tax (110% if AGI > $150k), else 90% current year
top-5: part-1/sec-1.1446-3 / part-1/sec-1.1446-0 / part-1/sec-1.6655-2T / part-1/sec-1.1446-3 / part-1/sec-1.904-7
grade: miss
Q: What use must a home office satisfy to qualify for the deduction?
expect: 26 CFR 1.280A-2: exclusive and regular use as principal place of business
top-5: part-1/sec-1.1441-1 / part-1/sec-1.274-5 / part-1/sec-1.280F-6 / part-1/sec-1.817-2 / part-1/sec-1.1503(d)-1
grade: suite-defect (excluded)
Q: How long must employers keep employment tax records?
expect: 26 CFR 31.6001-1 / related: at least 4 years after the due date or payment date
top-5: part-31/sec-31.6001-2 / part-35/sec-35.3405-1T / part-31/sec-31.6001-3 / part-1/sec-1.274-6T / part-1/sec-1.475(a)-4
grade: miss
Q: Which property qualifies for the section 179 expensing election?
expect: 26 CFR 1.179-1/.179-2: tangible personal property, certain off-the-shelf software, qualified real property
top-5: part-1/sec-1.179-1 / part-1/sec-1.179-3 / part-1/sec-1.179-1 / part-1/sec-1.179-3 / part-1/sec-1.179-1
grade: partial

Agent score

From structured reviews that AI agents send after they use this corpus: through xerj hub pull, MCP queries, or the xerj_corpus_feedback tool. Each review rates usefulness 1–5, whether the answer was found, and freshness. This is not the human hub star count shown above. The two are never mixed.

Loading agent reviews…

Score = Bayesian mean of usefulness (prior 3.0 with weight 5), so a few reviews cannot swing it. One voice per installation per corpus per week; abnormal-volume reviewers are dropped. Coverage gaps appear only once 3 or more agents report the same one. How it works.

Traffic

Traffic stats load from /api/hub-traffic when this page runs JavaScript.

Views: visits to this page (search-engine crawlers excluded). Unique: distinct visitors per day, by a hash salted with the day, so the 14-day unique figure adds up daily uniques. Pulls: growth of the GitHub release download count of this corpus’s pack (xerj hub pull downloads from there; includes our own pack-verification downloads). Searches: hosted-hub queries for this corpus. Referring sites appear after 3 views. What is collected.

Agent usage

Usage stats load from /api/hub-usage when this page runs JavaScript.

Counted: requests agents send to the hosted hub API (hub.xerj.org/api/v1/code, /def) for this corpus. Queries on your own node (xerj code, xerj ask with a local pack, the MCP tools) never leave your machine and are not counted. Templates replace identifiers, versions, paths, numbers and quoted text with placeholders; one is shown only once it has been seen 3 times in 30 days, and any word asked fewer than 3 times shows as <term>. Raw queries are never published. What is collected.