business-tax-schema

Business Tax Schema

Structured vocabulary and revision topology for C-corporation tax forms: federal Form 1120, Florida F-1120, and Form 5472 (foreign-owned corps). This skill provides the canonical field names, line mappings, and era-routing logic that downstream preparation skills depend on.

State-specific scope: Federal Form 1120 and Form 5472 content is nationally applicable. Florida F-1120 eras, exemption history, and line shifts use Florida as the reference state jurisdiction. Sections marked (Florida) contain state-specific content.

Era Routing

Every tax year maps to exactly one era for each jurisdiction. Determine the era first, then apply the era-specific line definitions and rules.

Federal 1120 Eras

• Pre-TCJA (2007-2017) — Graduated rates 15-35%, Section 199 deduction on Line 25, corporate AMT applies, NOL 2-year carryback / 20-year carryforward with 100% usage
• Post-TCJA (2018+) — Flat 21% rate, Section 199 repealed, no corporate AMT, NOL indefinite carryforward with 80% usage limit

The TCJA boundary at tax year 2018 is the single most important routing decision in federal return preparation. When a user asks about any Form 1120 line, rate, or deduction rule, resolve the era before answering.

Florida F-1120 Eras (Florida)

Four structural revisions, identified by form revision stamp:

• R-01-07 (2007-2011) — Emergency excise tax (EET) present, Schedule VI AMT active, taxpayer election field (E), $5,000 exemption
• R-01-13 (2012-2014) — EET dropped, line numbers shift from R-01-07, exemption increases ($25K in 2012, $50K from 2013), Schedule VI still present
• R-01-16 (2015-2017) — New credit lines added to Schedule V, email field added to contact section, Schedule VI AMT still active
• R-01-19 (2018+) — Schedule VI dropped entirely (mirrors federal AMT repeal), taxpayer election field removed, page 2 letter designators shift

FL corporate tax rate: 5.5% across all eras (2007-2025).

Florida Exemption History (Florida)

• 2007-2011 — $5,000
• 2012 — $25,000
• 2013-2025 — $50,000

The exemption amount is year-specific and independent of the revision era. Always look up the exact year, not the era bracket.

NOL Rules by Era

Rule	Pre-TCJA (2007-2017)	Post-TCJA (2018+)
Carryback	2 years (optional)	Not allowed*
Carryforward	20 years	Indefinite
Usage limit	100% of taxable income	80% of taxable income

*CARES Act exception: NOLs arising in 2018-2020 could be carried back 5 years.

The NOL era determines which rules apply to the loss year of origin, not the utilization year. A pre-TCJA NOL being used in a post-TCJA year retains its 20-year carryforward window but is subject to the 80% limitation in the utilization year.

Form 5472

Required every year for C-corps with 25%+ foreign ownership (IRC 6038A).

• Penalty: $25,000 per form for failure to file
• Parts I-VI: reporting entity info, related party details, monetary transactions, nonmonetary transactions, additional information
• Attached to the Form 1120 — not filed separately
• Required even if no reportable transactions occurred during the year

Concept Mapping

The schema uses a three-layer vocabulary:

1. Inventory fields — Internal names from data extraction (e.g., gross_receipts, officer_compensation)
2. Form lines — IRS/state form line identifiers (e.g., 1120.Line_1a, F-1120.Line_1)
3. Concept names — Canonical business concepts that bridge inventory to form (e.g., gross_revenue, officer_comp)

When mapping an inventory field to a form line:

1. Look up the inventory field in the concept map to get the canonical concept name
2. Resolve the tax year to an era
3. Use the era-specific line definitions to get the target form line
4. Validate that the line exists in that era (lines shift between revisions)

source_ref Notation

Data lineage in schema files uses source_ref to trace values back to extraction:

source_ref: "extracted_values[field=gross_receipts]"

Revision Topology

Line numbers are not stable across revisions. When working with historical returns or multi-year comparisons, always verify line definitions against the correct era.

Federal Line Shifts (TCJA Boundary)

Key changes at the 2017-2018 boundary:

• Line 25 (Section 199 domestic production deduction) — present pre-TCJA, removed post-TCJA
• Line 29a/29b (NOL deduction) — carryback election line removed post-TCJA
• Schedule C (DRD) — computation unchanged but AMT interaction removed
• Tax rate schedule — graduated table replaced by flat 21% on Line 31

Florida Line Shifts (Florida)

Cross-revision changes to watch:

• R-01-07 to R-01-13: EET lines removed, line numbers renumber from that point down; exemption amount field changes
• R-01-13 to R-01-16: Credit lines added to Schedule V (insertion, not renumber); email field added to contact block
• R-01-16 to R-01-19: Schedule VI AMT dropped entirely; taxpayer election field (E) removed; page 2 letter designators shift

Adding a New Tax Year

1. Create expectations file using the prior year as template
2. Verify the FL revision era — if a new revision stamp appears, update the era file or create a new one
3. Check for federal law changes requiring a revision update (rate changes, new deductions, new schedules)
4. Run assess-year validation against the new expectations

Historical Form Sourcing

Each tax year requires year-specific source forms. Current-year forms do not document historical line structures.

• IRS Prior Archive (2007-2024) — irs.gov/pub/irs-prior/i1120--{year}.pdf
• TaxFormFinder FL (2011-2024) — taxformfinder.org/forms/{year}/{year}-florida-form-f-1120.pdf
• eformrs.com FL (2007-2010) — eformrs.com/Forms{yy}/States{yy}/FL/FL1120.pdf

Use the IRS prior archive as authoritative for federal line definitions. Use TaxFormFinder or eformrs for Florida forms depending on the year range.

Validation Sources

External references for verifying schema accuracy:

• IRS Section 199 Repeal — irc.bloombergtax.com/public/uscode/doc/irc/section_199
• FL Statutes 220.14 (corporate income tax) — flsenate.gov/Laws/Statutes/2024/0220.14
• FL DOR Corporate Income Tax — floridarevenue.com/taxes/taxesfees/Pages/corporate.aspx

Supporting References

Read these for field-level detail and structured data:

• references/business-tax-schema.md — Full schema source with concept vocabulary, file routing table for YAML data files (concept-map, core form definitions, revision-era files, per-year expectations), revision-to-year mapping tables, NOL rules, FL exemption history, Form 5472 overview, historical form sourcing URLs, and new-year onboarding procedure. Read when you need the YAML file routing table, the source_ref notation spec, or the canonical era-to-year mapping.

Cross-Plugin References

For GL account structure that feeds tax line mapping:

• Invoke accounting-foundation:chart-of-accounts for account numbering, Form 1120 tax-line mapping at the GL level, and book-tax difference classification

For entity context affecting form selection:

• Invoke accounting-foundation:entity-profile for corporate entity type, ownership structure (triggers Form 5472), fiscal year, and state nexus

For financial data flowing into tax forms:

• Invoke accounting-foundation:financial-statements for income statement and balance sheet presentation that maps to Form 1120 schedules
• Invoke bookkeeping:monthly-close for period-end financials that feed return preparation

For platform-level field extraction:

• Invoke qbo-integration:qbo-reporting for QBO report data that maps to schema inventory fields
• Invoke qbo-integration:qbo-audit for QBO tax data extraction and audit trail

Cross-Plugin Consumers

Skills that depend on this schema for form structure and line definitions:

• tax-prep:form-1120-prep — federal Form 1120 line definitions, era routing, and field-to-line mapping for return assembly
• tax-prep:state-returns — Florida F-1120 revision topology, era-specific line numbers, and exemption amounts
• tax-prep:tax-forms — supporting schedule structure and line vocabulary across form types
• tax-prep:nol-tracking — NOL era rules (carryback/carryforward windows, usage limits) and CARES Act exceptions
• tax-prep:tax-compliance — filing requirement rules that depend on form revision and era
• tax-prep:e-filing — form field identifiers for electronic filing package assembly
• tax-prep:tax-planning — era-specific rate tables and deduction availability for planning scenarios
• financial-planning:tax-provision — federal and state rate tables, TCJA boundary logic for ASC 740 provision computation