Library

The authority behind every answer

Every response cites the exact source it came from. Open the marker and read the law yourself.

127,000+

sections of primary authority

174

distinct sources

52

jurisdictions: federal + 50 states + DC

CorpusJurisdictionWhat it covers

Treasury RegulationsFederaleCFR Title 26: final regulations, section-by-sectionecfr.gov

Internal Revenue CodeFederalTitle 26 statutes: full coverage including Subchapter Kuscode.house.gov

IRS Written DeterminationsFederal12,650 PLRs, TAMs and Chief Counsel Advice, 1999 to presentirs.gov

U.S. Tax Court OpinionsFederalT.C. and memorandum opinions via the court's DAWSON systemustaxcourt.gov

Income Tax TreatiesFederalTreaty instruments and technical explanations, 69 countriestreasury.gov

Revenue & Taxation CodeCaliforniaState tax statutes:income, franchise, sales and property taxleginfo.legislature.ca.gov

Tax StatutesDelawareState tax statutes:corporate franchise and income taxdelcode.delaware.gov

Tax StatutesLouisianaState tax statutes and administrative provisionslegis.la.gov

Tax StatutesNew JerseyState tax statutes:gross income, corporate business taxnjleg.state.nj.us

Tax StatutesKansasState tax statutes:income, sales and property taxksrevisor.gov

Tax StatutesOregonState tax statutes:income and corporate excise taxoregonlegislature.gov

Tax StatutesTexasState tax statutes:franchise, sales and use taxstatutes.capitol.texas.gov

Treasury RegulationsFederaleCFR Title 26: final regulations, section-by-sectionecfr.gov

Internal Revenue CodeFederalTitle 26 statutes: full coverage including Subchapter Kuscode.house.gov

IRS Written DeterminationsFederal12,650 PLRs, TAMs and Chief Counsel Advice, 1999 to presentirs.gov

U.S. Tax Court OpinionsFederalT.C. and memorandum opinions via the court's DAWSON systemustaxcourt.gov

Income Tax TreatiesFederalTreaty instruments and technical explanations, 69 countriestreasury.gov

Revenue & Taxation CodeCaliforniaState tax statutes:income, franchise, sales and property taxleginfo.legislature.ca.gov

Tax StatutesDelawareState tax statutes:corporate franchise and income taxdelcode.delaware.gov

Tax StatutesLouisianaState tax statutes and administrative provisionslegis.la.gov

Tax StatutesNew JerseyState tax statutes:gross income, corporate business taxnjleg.state.nj.us

Tax StatutesKansasState tax statutes:income, sales and property taxksrevisor.gov

Tax StatutesOregonState tax statutes:income and corporate excise taxoregonlegislature.gov

Tax StatutesTexasState tax statutes:franchise, sales and use taxstatutes.capitol.texas.gov

+ 162 more sources across 50 states and federal, 127,000+ sections in total

Counts as of September 2026.

Full coverage

Everything in the library today: counts as of September 2026.

Federal

Internal Revenue Code2,161 sections

Title 26 statutes, current through the latest OLRC release point

Treasury Regulations6,155 sections

26 C.F.R.: final regulations from the eCFR

IRS Written Determinations12,650 documents

Taxpayer-specific rulings and internal legal advice released under § 6110

·Private Letter Rulings · 2015–present
·Chief Counsel Advice · 1999–present
·Technical Advice Memoranda · 1999–present

Internal Revenue Bulletin1,945 items

Revenue rulings, revenue procedures, notices and announcements

Internal Revenue Manual1,751 sections

The IRS's operating manual: exam, collection, appeals, penalties

U.S. Tax Court Opinions1,541 opinions

T.C. and memorandum opinions, 2018–present, with appeal status

IRS Forms & Instructions183 documents

Current instructions plus prior-year editions (TY2022–2024)

IRS Publications57 publications

Practitioner guidance: Pub 541, Pub 17, Pub 590 and more

Income Tax Treaties166 documents

Treaty instruments and technical explanations for 69 countries

P.L. 86-272 & interstate commerce5 documents

15 U.S.C. §§ 381–384 plus the MTC solicitation-immunity statement

States: all 50 + the District of Columbia

AlabamaAlaskaArizonaArkansasCaliforniaColoradoConnecticutDelawareDistrict of ColumbiaFloridaGeorgiaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming

Citation-first by design: every AI response ties back to a primary source from this library. Client data is never used to train models.

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