Compendium

Tax-Form / E-Filing / Structured-Tax DSLs Family Index

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Tax-Form / E-Filing / Structured-Tax DSLs Family Index

type: language-family-index family: tax-forms languages_catalogued: 27 tags: [language-reference, family-index, tax-forms, irs-mef, iris, fire, txf, ofx, fatca, crs, cbcr, globe, ixbrl, mtd, cfdi, sped, efw2]

Tax-Form / E-Filing / Structured-Tax — Family Index

Family overview

Tax-form DSLs are the textual languages used to encode tax filings, tax-return data interchange, and government tax-form schemas. Unlike accounting interchange formats (the financial-regulatory family — XBRL, ISO 20022, Peppol invoicing), tax-form formats encode the line items of a specific government return: an IRS Form 1040 with all its schedules, an HMRC CT600 with its iXBRL-tagged accounts, a Mexican CFDI invoice carrying VAT-equivalent withholdings. The dominant pattern since the mid-2000s has been annual XML schemas published by a tax authority, regenerated each tax year against the year’s statutory form line numbers — IRS Modernized e-File (MeF, 2004+) being the canonical example, with separate schema bundles per form family (1040, 1120, 1065, 990, 941, 2290, 709, 1042) and per tax year (TY2025 schemas live for processing year 2026, TY2026 in development).

The US side of the family has two parallel rails. MeF handles the return itself: 1040 individual, 1120 corporate, 1065 partnership, 990 exempt-org, 941 employment, etc., with version v5.2 of the TY2025 individual MeF schemas released in late 2025 against WSDL R10.9. IRIS (Information Returns Intake System) handles the information returns about a taxpayer: 1099-NEC, 1099-MISC, 1099-INT, 1099-DIV, 1042-S, etc. IRIS is replacing the four-decade-old fixed-width FIRE (Filing Information Returns Electronically) system: Tax Year 2025 (filed early 2026) is the last year FIRE accepts new filings, with FIRE retirement scheduled for December 31, 2026 and IRIS as the sole intake path for the Tax Year 2026 filing season (early 2027). Above the federal layer sits state-tax fragmentation: each US state operating an income or business tax (CA FTB, NY DTF, IL DOR, etc.) publishes its own XML schema, frequently as an MeF-style payload that piggy-backs on the federal MeF transmission (“Fed/State e-file”). Wage reporting goes to a different agency entirely — SSA EFW2 is the 512-byte fixed-width COBOL-era format for annual W-2 filings, still mandatory in 2026.

The international layer is dominated by OECD-led tax-information-exchange schemas: CRS (Common Reporting Standard) for automatic exchange of financial-account information between tax authorities — schema v3.0 published Oct 2024, used for CRS 2.0 reporting that begins with 2026 reporting year data exchanged in 2027; FATCA (US-driven, 2014) the older US-specific cousin still in production; CbCR (Country-by-Country Reporting, BEPS Action 13) at schema v2.0 since June 2019; and the newest layer, BEPS Pillar Two GIR (GloBE Information Return), with XML schema published January 2025 and a first global lodgment deadline of 30 June 2026 for large multinationals subject to the 15% global minimum tax. National tax authorities outside the US run their own stacks: HMRC mandated iXBRL for all UK Corporation Tax filings since 1 April 2011 (and HMRC confirmed in July 2025 that MTD for Corporation Tax is cancelled, so iXBRL-via-CT600 remains the UK-CT path indefinitely); HMRC’s Making Tax Digital for VAT has been in force since April 2022 and MTD-ITSA expands to taxpayers with income above £50,000 from April 2026; the ATO runs MyTax with pre-fill; CRA runs T2 corporate XML; Brazil’s SPED / eSocial / NF-e stack is the most aggressive in the world, with NF-e mandatory for all states from January 2026 and a 2026 tax reform triggering a new e-invoice layout.

A separate consumer-facing rail exists for importing tax data into desktop tax-prep software. TXF (Tax eXchange Format) — the tagged-text format Intuit promulgated in ~1991, current spec v042 frozen since 2012 — remains the lingua franca for getting 1099-B brokerage data out of TurboTax/Quicken/H&R Block, despite being moribund as a spec; OFX (Open Financial Exchange) is the XML successor with explicit 1099-B/INT/DIV tax-import support via the OFX Tax Extension (current TY2020 spec, OFX 2.3 base); FDX (Financial Data Exchange) JSON is the industry-blessed forward path, gradually displacing OFX. Mexico’s CFDI 4.0 is the global outlier: a server-side e-invoice clearance model where SAT signs every invoice in real time, with a March 2026 catalog update, a Hydrocarbons add-on mandatory from March 25 2026, and a May 1 2026 real-time data-access mandate for digital platforms — effectively turning every B2B/B2C transaction in Mexico into a tax filing.

In our deep library

None catalogued. Tax-form DSLs are tax-authority schemas (XML/JSON/fixed-width), not standalone host languages, so no Tier 1/Tier 2 deep notes exist.

Cross-reference:

  • financial-regulatory — sibling family, covers XBRL/iXBRL, ISO 20022, FpML, Peppol BIS Billing 3.0; the iXBRL listed below is the HMRC-CT-specific instantiation, the general XBRL standard lives in financial-regulatory.
  • api-description — XML Schema (XSD) is the underlying technology for nearly every entry in this family; WSDL drives MeF transmission contracts.
  • retail-supplychain — e-invoicing overlap: Peppol BIS Billing 3.0, EDIFACT INVOIC, UBL Invoice all carry VAT/GST line items that have tax-compliance implications.
  • citation-formats — regulatory citation conventions for IRC, Treas. Reg., HMRC manuals.
  • notation-spec — formal grammars and tagging conventions.
  • government-civictech — overlap on government-published machine-readable formats.

Tier 3 family table — US federal tax filing

FormatFirst appearedOriginTypeStatus (2026)URL
IRS MeF (Modernized e-File) — umbrella2004IRSSOAP/WSDL transmission wrapping per-form XML payloads; current WSDL R10.9 for processing year 2026Active, TY2025 schemas live (individual schema v5.2 released late 2025); TY2026 in developmenthttps://www.irs.gov/e-file-providers/modernized-e-file-mef-status
MeF 1040 (Individual)2004 (1040 added 2010 for full e-file)IRSXML schema per tax year; ~600+ forms and schedules coveredActive — TY2025 schemas in production for filing season 2026https://www.irs.gov/e-file-providers/release-memo-for-tax-year-2025-modernized-e-file-schema-and-business-rules-for-individual-tax-returns-version-5-point-2
MeF 1120 / 1120S (Corporate / S-Corp)2004IRSXML schemaActivehttps://www.irs.gov/e-file-providers/modernized-e-file-mef-schemas-and-business-rules
MeF 1065 (Partnership)2006IRSXML schemaActivehttps://www.irs.gov/e-file-providers/modernized-e-file-mef-schemas-and-business-rules
MeF 990 (Exempt Org)2004IRSXML schema; underlies the public Form 990 dataset on IRS.gov / ProPublica Nonprofit ExplorerActive, mandatory e-file for nearly all 990 filers since 2020 (Taxpayer First Act)https://www.irs.gov/e-file-providers/modernized-e-file-mef-schemas-and-business-rules
MeF 941 / 940 (Employment)2006IRSXML schema, quarterlyActive — TY2025 employment-tax schemas livehttps://www.irs.gov/e-file-providers/tax-year-2025-schemas-and-business-rules-for-employment-tax-modernized-e-file-mef-forms
MeF 2290 (Heavy Vehicle Use)2007IRSXML schemaActive — TY2025 schemas livehttps://www.irs.gov/tax-professionals/tax-year-2025-valid-xml-schemas-and-business-rules-for-form-2290-modernized-e-file-mef
MeF 1042 / 1042-S (Withholding)2014 (1042-S), 2024 (1042 itself)IRSXML schemaActive — 2025 schemas livehttps://www.irs.gov/tax-professionals/2025-valid-xml-schemas-and-business-rules-for-1042-modernized-e-file-mef
MeF 709 / 709-NA (Gift Tax)2025IRSXML schema; new e-file pathNew — first year of 709 e-file is 2025https://www.irs.gov/tax-professionals/2025-xml-schemas-and-business-rules-for-form-709709-na-modernized-e-file-mef
IRIS (Information Returns Intake System)2023IRSXML transmission for 1099-series and 1042-S info returns; modern replacement for FIREActive and expanding; sole 1099 intake path from TY2026 (filed early 2027)https://www.irs.gov/filing/e-file-forms-1099-with-iris
FIRE (Filing Information Returns Electronically)~1986IRSFixed-width text records, EBCDIC-derived; 1099-series, 5498, 8027, 1098, etc.Sunsetting — TY2025 is the last year FIRE accepts new filings; retirement Dec 31, 2026https://www.irs.gov/e-file-providers/filing-information-returns-electronically-fire
SSA EFW2 / EFW2C (W-2 / W-2c)1980s (modern EFW2 ~2001)SSAFixed-width 512-byte records (RA/RE/RW/RO/RS/RT/RU/RV/RF); ASCII; one of the oldest schemas still in mandatory productionActive, TY2025 spec v3.3 (Jan 2026); validated via SSA AccuWage; TY2025 SSA upload due Feb 2, 2026https://www.ssa.gov/employer/EFW2&EFW2C.htm
ACA 1094/1095 (Affordable Care Act)2015IRS / DOLXML via AIR (Affordable Care Act Information Returns) channel; large-employer health-coverage reportingActive, AIR remains the channel even as IRIS subsumes other 1099shttps://www.irs.gov/e-file-providers/air/affordable-care-act-information-return-air-program
Schedule K-1 (1041/1065/1120-S)within MeF (2004+)IRSXML schedules transmitted inside parent return; pass-through entity reportingActivehttps://www.irs.gov/e-file-providers/modernized-e-file-mef-schemas-and-business-rules

Tier 3 family table — US state tax filing

FormatFirst appearedOriginTypeStatus (2026)URL
State Fed/State MeF (umbrella, 40+ states)2004+ (per state)FTA (Federation of Tax Administrators) joint program with IRSState-specific XML schemas riding the federal MeF transmission rail; each state publishes its ownActive; each state’s schema is independently versionedhttps://www.taxadmin.org/fta-and-the-irs
California FTB e-file (540 / 100 / 565 / 568)2003+CA Franchise Tax BoardXML schema (state-specific to FTB); standalone or piggy-backed on federal MeFActive, annually updatedhttps://www.ftb.ca.gov/tax-pros/e-file/business-electronic-filing/xml-schemas.html
New York DTF e-file2003+NY Department of Taxation and FinanceXML schemaActivehttps://www.tax.ny.gov/bus/efile/
Other state schemas (IL, TX, PA, NJ, FL, etc.)rolling, 2003-2015Each state revenue deptPer-state XML; minor variations on FTA templateActive; significant compliance burden for multi-state tax softwarehttps://www.taxadmin.org/

Tier 3 family table — International tax exchange

FormatFirst appearedOriginTypeStatus (2026)URL
OECD CRS (Common Reporting Standard) XML2014 (schema v1.0); v3.0 Oct 2024OECDXML schema for automatic exchange of financial-account information between tax authoritiesCRS 2.0 — schema v3.0 / User Guide v4.0 effective for 2026 reporting year, first exchanges 2027https://www.oecd.org/en/publications/amended-common-reporting-standard-xml-schema_dd7ee57a-en.html
FATCA (Foreign Account Tax Compliance Act) XML2014IRS / US TreasuryXML schema for foreign financial institutions reporting US-person account data; predates CRS conceptuallyActive (v2.0); the US has not joined CRS, so FATCA is the US-specific channelhttps://www.irs.gov/businesses/corporations/fatca-xml-schemas-and-business-rules-for-form-8966
OECD CbCR (Country-by-Country Reporting, BEPS Action 13) XML2016 (v1.0); v2.0 June 2019OECDXML schema for MNE groups (>EUR 750m revenue) to report per-country revenue, profit, tax, employeesActive at v2.0; unchanged since 2019https://www.oecd.org/en/topics/country-by-country-reporting-for-tax-purposes.html
OECD GIR (GloBE Information Return, BEPS Pillar Two) XMLJanuary 2025 (schema published)OECD/G20 Inclusive FrameworkXML schema for the 15% global minimum tax return; supports both domestic filing and tax-administration exchangeNew — first global GIR lodgment deadline 30 June 2026; further safe-harbour-related schema work due H1 2026https://www.oecd.org/en/publications/globe-information-return-pillar-two-xml-schema_c594935a-en.html
OECD Crypto-Asset Reporting Framework (CARF) XMLJune 2023 (final), schema published 2024OECDXML schema for automatic exchange of crypto-asset transaction info; the CRS-equivalent for cryptoNew, first reporting 2027 (covering 2026 data) in early-adopter jurisdictionshttps://www.oecd.org/tax/exchange-of-tax-information/crypto-asset-reporting-framework.htm
EU DAC6 / DAC7 / DAC8 XML2020 (DAC6) / 2023 (DAC7) / 2025 (DAC8)EU CommissionXML schemas piggy-backing on OECD frameworks (DAC6=cross-border arrangements, DAC7=digital platforms, DAC8=crypto)Active (DAC6/DAC7); DAC8 transposition deadline Dec 31 2025, applies from Jan 2026https://taxation-customs.ec.europa.eu/taxation/tax-co-operation-and-control/general-overview/enhanced-administrative-cooperation-field-direct-taxation_en

Tier 3 family table — National tax authorities (non-US)

FormatFirst appearedOriginTypeStatus (2026)URL
HMRC iXBRL for Corporation Tax (CT600 + accounts)1 April 2011HMRC + UK FRCInline XBRL embedding XBRL tags inside the HTML of company accounts; mandatory for all UK CT returnsActive and entrenched — July 2025 HMRC roadmap confirmed MTD for Corporation Tax is cancelled, so iXBRL-via-CT600 is the UK CT path indefinitely; HMRC’s free online CT filing service closed 31 March 2026https://www.gov.uk/government/publications/xbrl-guide-for-uk-businesses/xbrl-guide-for-uk-businesses
HMRC Self Assessment SA100 XML~2000HMRCXML schema for individual income-tax filings via Self Assessment OnlineActivehttps://www.gov.uk/log-in-file-self-assessment-tax-return
HMRC Making Tax Digital (MTD) for VATApril 2019 (volunteer), April 2022 (mandatory)HMRCJSON-over-REST API; quarterly VAT submissions from digital recordsActive, mandatory for all VAT-registered businesses since April 2022https://www.gov.uk/government/collections/making-tax-digital-for-vat
HMRC MTD for Income Tax Self Assessment (MTD ITSA)April 2026 (first phase)HMRCJSON-over-REST API; quarterly digital reportingNew rollout — April 2026 for taxpayers with self-employment / property income above £50,000; lower thresholds phased through 2028https://www.gov.uk/government/collections/making-tax-digital-for-income-tax
CRA T2 Corporate XML / EFILE~1999Canada Revenue AgencyXML schema for federal corporate tax (T2); EFILE channelActivehttps://www.canada.ca/en/revenue-agency/services/e-services/businesses/corporation-internet-filing.html
ATO MyTax / Standard Business Reporting (SBR) XBRL2010 (SBR launch) / 2014 (MyTax)Australian Taxation OfficeSBR uses XBRL for business reporting; MyTax is the consumer pre-fill / lodgement portalActivehttps://www.sbr.gov.au/
Mexico SAT CFDI 4.02014 (CFDI 3.x), CFDI 4.0 effective Jan 2022, mandatory April 2023Mexico SATXML invoice schema with real-time SAT digital signature (“PAC” certification model); every B2B/B2C transaction is effectively a tax filingActive and expanding — March 2 2026 catalog update; March 25 2026 mandatory Hydrocarbons add-on; May 1 2026 real-time data-access mandate for digital platformshttps://www.sat.gob.mx/
Brazil SPED (Sistema Público de Escrituração Digital)2007Receita FederalUmbrella: SPED Fiscal (ICMS/IPI), SPED Contribuições (PIS/COFINS), ECF (corp income), ECD (accounting) — fixed-width and XMLActive; 2026 tax reform triggers new e-invoice layoutshttp://sped.rfb.gov.br/
Brazil eSocial2014 (phased)Receita Federal + Ministry of LabourXML schema for labour and social-security obligations; replacing DIRF in 2026Active — Manual v S-1.3 (2026); April 2026 competence S-1200/S-1210 due May 15 2026https://www.gov.br/esocial/pt-br
Brazil NF-e / NFC-e / NFS-e2006 (NF-e)Receita + state SEFAZXML invoice schemas; NF-e (B2B goods), NFC-e (consumer), NFS-e (services); national NFS-e standard mandatory for Simples Nacional from Sept 1 2026Active; all states require NFC-e from Jan 1 2026 (end of hardware fiscal printers)https://www.nfe.fazenda.gov.br/
India ITD e-Filing XML / JSON (ITR-1..7)2006+Income Tax Department of IndiaPer-form schemas (ITR-1 through ITR-7); XML historically, JSON for newer ITRs; integrated with the Compliance PortalActivehttps://www.incometax.gov.in/iec/foportal/

Tier 3 family table — Consumer-import / brokerage

FormatFirst appearedOriginTypeStatus (2026)URL
TXF (Tax eXchange Format)~1991Turbo Tax Group / industry; spec maintained at taxdataexchange.orgTagged-text format with reference-number-keyed records; per-form tags (e.g. N321 = 1099-INT box 1)Dormant spec (v042 frozen since 2012) but still widely used — most US brokers export TXF for TurboTax / TaxAct / H&R Block importhttps://taxdataexchange.org/docs/txf/v042/index.html
OFX (Open Financial Exchange) — base1997Microsoft + Intuit + CheckFreeXML/SGML financial data interchange; latest OFX 2.3Active (maintained by FDX); the financial-data half is mostly displaced by FDX JSONhttps://financialdataexchange.org/
OFX Tax Extension (1099/W-2 import)2003+Intuit / FDXXML extension to OFX carrying 1099-B/INT/DIV/MISC/OID/R + W-2 data; tax-year-specific releasesActive — current TY2020 spec; tax-import-from-broker workhorse alongside TXFhttps://financialdataexchange.org/common/Uploaded%20files/OFX%20files/OFXTax.2020.0.pdf
FDX (Financial Data Exchange) JSON2018Financial Data Exchange consortium (Plaid, Intuit, banks)OAuth + REST + JSON; modern replacement for OFXActive — industry direction; FDX is the successor to both OFX and screen-scrapinghttps://financialdataexchange.org/
Proprietary tax-prep software files (TurboTax .tax2025, H&R Block .t25, Drake, Lacerte, ProSeries)varies, mostly 1990sIntuit / H&R Block / Drake / CCHProprietary binary or encrypted XML; export paths to TXF or MeF/state XMLActive but vendor-locked; not interoperable across vendors except via exportvaries per vendor
CSV broker exports (Wealthsimple, Robinhood, IBKR, Schwab, Fidelity, Coinbase)2010sEach brokerNon-standard CSV / Excel; user must map columns to tax-software import schemaActive, the practical reality for crypto and many newer brokers; tax-prep software has dedicated CSV-import wizardsvaries per broker

Notable threads

  • MeF as the persistent dominant US e-filing standard. IRS Modernized e-File launched in 2004 with the 1120 corporate return and has expanded to nearly every federal return: 1040, 1065, 990, 941, 940, 2290, 1042, and as of 2025 even Form 709 (gift tax). The architecture is SOAP/WSDL transmission with per-tax-year XML schema bundles signed by IRS digital certs. The remarkable feature is stability: 22 years of continuous operation with year-over-year schema versioning (TY2025 individual schema is v5.2, on WSDL R10.9). Tax-software vendors must regenerate their MeF mapping every fall as the IRS publishes the next year’s schemas — a treadmill that creates a moat against new entrants.

  • The FIRE-to-IRIS transition is finally happening. IRS FIRE (Filing Information Returns Electronically) has been the 1099 e-file channel since the mid-1980s, originally an SSA-style 750/512-byte fixed-width format. After multiple aborted modernization attempts, IRIS is now the replacement: a 2023-launched XML-based system that as of 2026 supports the entire 1099 series plus 1042-S. The retirement date is concrete this time — Dec 31 2026 — and Tax Year 2026 returns (filed early 2027) must go through IRIS. Every TCC (Transmitter Control Code) must be re-applied for under IRIS, a non-trivial migration for the thousands of bulk filers who have been on FIRE for decades.

  • State-tax fragmentation: the practical cost of US federalism. The FTA’s Fed/State e-file program piggy-backs state returns on the federal MeF transmission, but each state’s schema is sovereign. California FTB publishes its own XSDs for Forms 540 (individual), 100 (corporate), 565 (partnership), 568 (LLC); New York DTF, Illinois DOR, Pennsylvania DOR, etc. each do the same. Multi-state tax software (Lacerte, Drake, ProSystem fx) must maintain 40+ separate schema mappings and re-test against each state’s ATS environment annually. This is the single biggest compliance cost in US tax-software development.

  • OECD CRS, FATCA, and the cross-border information-exchange stack. FATCA (2014, US-driven, US-only-inbound) established the pattern: foreign financial institutions report US-person accounts to the IRS via XML. CRS (also 2014, OECD-led, ~120 jurisdictions reciprocal) extends it globally and is now the dominant standard — except that the US has not joined CRS, leaving FATCA as the US channel. CRS 2.0 with XML schema v3.0 took effect for the 2026 reporting year (first exchanges 2027); it adds crypto-asset coverage, electronic-money providers, and tightens the indicia rules. CARF (Crypto-Asset Reporting Framework) is the parallel crypto-specific channel.

  • BEPS Pillar Two GIR is the newest international layer. The OECD’s 15% global minimum tax for MNEs >EUR 750m revenue went live for fiscal years starting on or after 31 Dec 2023 in early-adopter jurisdictions (EU, UK, Japan, Korea, Canada, Australia). The GloBE Information Return (GIR) XML schema was published January 2025, with the first global lodgment deadline 30 June 2026 — a date the international tax-tech vendors (Wolters Kluwer CCH, Thomson Reuters ONESOURCE, Vertex) have been preparing for since 2024. Safe-harbour-related schema refinements are due in the first half of 2026.

  • Mexico CFDI 4.0 as the global model for “e-invoicing as tax filing”. Mexico’s SAT operates the world’s most aggressive real-time tax-clearance model: every B2B and B2C invoice must be (1) signed locally by the issuer’s private key, (2) submitted to a SAT-certified PAC (Proveedor Autorizado de Certificación), (3) signed by SAT in real time, and (4) returned to the issuer with the SAT seal before it is legally valid. CFDI 4.0 (effective Jan 2022, mandatory April 2023) tightened taxpayer-data validation. 2026 brought a March catalog update, a mandatory Hydrocarbons/Petroleum add-on from March 25, and a real-time data-access mandate for digital platforms from May 1. Brazil’s SPED/NF-e is the older cousin; many countries (Italy SDI, Poland KSeF, France’s planned 2026 mandate) are following the same pattern.

  • HMRC iXBRL’s surprising longevity, MTD-CT’s quiet death. HMRC has required iXBRL-tagged accounts and computations with every Corporation Tax (CT600) return since 1 April 2011 — one of the world’s largest mandatory XBRL deployments. The expected successor was Making Tax Digital for Corporation Tax, but in HMRC’s July 2025 Transformation Roadmap, the agency confirmed it has no intention of introducing MTD for CT — a full cancellation, not a delay. MTD remains in force for VAT (since 2022) and is expanding to Income Tax Self Assessment from April 2026 for taxpayers >£50,000. So iXBRL-via-CT600 is the UK CT filing path for the foreseeable future, and HMRC’s free CT online filing service closed 31 March 2026 to push small companies onto commercial iXBRL software.

  • TXF’s zombie persistence. TXF v042 — the spec hasn’t moved since 2012 — was supposed to be replaced years ago by OFX Tax Extension, then by FDX JSON. Yet TXF is still what every US broker exports for TurboTax/H&R Block/TaxAct import. The reason is brutal Conway’s-Law lock-in: the desktop tax-prep importers are huge codebases that work, and changing the parser produces zero customer-visible value while introducing year-end-bug risk. FDX is winning the live-data financial-aggregation war (replacing OFX/Plaid screen-scraping), but the annual tax-import use case — where you only run the import once, in February — has zero pressure to migrate. Expect TXF to outlive most of the people who wrote the v042 spec.

Citations

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