Contains verified nexus determination framework (physical presence, economic/factor presence thresholds, P.L. 86-272 protection analysis), state income tax computation walkthrough with year-by-year variance tables (2007-2026), and state e-filing mandate/penalty schedules. State corporate income tax, apportionment, single sales factor, market-based sourcing, multistate filing, NOL carryforward, estimated tax, voluntary disclosure, state modifications to federal taxable income. Consult when preparing any state corporate income tax return, evaluating whether a C-corporation has nexus in a state, computing apportioned state taxable income, determining state e-file obligations, analyzing P.L. 86-272 protection for service vs. tangible property companies, or researching state-specific NOL rules and conformity dates.
Contains verified nexus determination framework (physical presence, economic/factor presence thresholds, P.L. 86-272 protection analysis), state income tax computation walkthrough with year-by-year variance tables (2007-2026), and state e-filing mandate/penalty schedules. State corporate income tax, apportionment, single sales factor, market-based sourcing, multistate filing, NOL carryforward, estimated tax, voluntary disclosure, state modifications to federal taxable income. Consult when preparing any state corporate income tax return, evaluating whether a C-corporation has nexus in a state, computing apportioned state taxable income, determining state e-file obligations, analyzing P.L. 86-272 protection for service vs. tangible property companies, or researching state-specific NOL rules and conformity dates.
State Returns
Operational skill for state corporate income tax return preparation, with deep coverage of
Florida F-1120 and a framework for expanding to additional states as filing obligations arise.
State-specific scope: Nexus determination, apportionment concepts, P.L. 86-272, and
the multistate filing framework are nationally applicable. The detailed return preparation
walkthrough uses Florida (Form F-1120) as the reference state jurisdiction. Sections
marked (Florida) contain state-specific content. Practitioners in other states should
substitute their state's rules for the Florida-specific sections below.
Nexus Determination
Nexus is the minimum connection giving a state authority to impose income tax. Evaluate
every state where the corporation has activity using three tests in order.
Physical Presence Nexus
Any of these facts creates nexus in the state:
Employees working in the state (including remote workers)
Owned or leased real or personal property
Inventory stored in the state (including third-party FBA warehouses)
Regular solicitation visits by company representatives
Economic Nexus / Factor Presence
Post-Wayfair (2018), states increasingly apply economic nexus to income tax. The MTC
factor presence standard triggers nexus if any single factor is met:
Property in state >= $500,000
Payroll in state >= $500,000
Sales sourced to state >= $500,000
25%+ of total property, payroll, or sales in state
States with some form of income tax economic nexus include CA, CO, CT, HI, MA, MI, NY,
OH, OR, PA, WA, and others. Each state sets its own thresholds; verify the specific
state's current law before concluding no nexus.
P.L. 86-272 Protection
Federal law (15 USC 381-384) prohibits net income tax when the only in-state activity is
solicitation of orders for tangible personal property, where orders are sent out of state
for approval and filled/shipped from outside the state.
Protected activities: In-person/phone/mail solicitation for tangible personal property;
ancillary activities (advertising, carrying samples).
Not protected (nexus exists despite P.L. 86-272):
Sales of services or intangibles
Leasing tangible personal property
Maintaining an office or warehouse in the state
Approving or filling orders in the state
Collecting delinquent accounts in the state
Post-2021: Many states treat extensive web-based interactivity (cookies, app
interactions, marketplace facilitation) as exceeding solicitation per MTC revised guidance
For service-only corporations: P.L. 86-272 provides zero protection. Nexus is
determined solely by physical presence and factor presence tests.
Nexus Evaluation Workflow
List every state with any corporate activity (employees, property, sales, contractors)
For each state, apply physical presence test
If no physical presence, apply the state's economic nexus thresholds
If nexus exists, check P.L. 86-272 — only protects tangible personal property sales
Result: list of states where a return must be filed
Florida Corporate Income Tax (Florida — Form F-1120)
Filing Obligation
Every corporation with Florida nexus must file Form F-1120 annually if federal taxable
income (plus Florida additions) exceeds $50,000. This includes C-corporations, LLCs taxed
as corporations, tax-exempt organizations with UBTI, banks, and certain partnerships with
corporate members. A return is required even if no tax is due.
Tax Rate and Exemption
Standard rate: 5.5% of Florida taxable income
Exemption: $50,000 (not a deduction; income up to $50,000 is exempt)
No personal income tax: Florida taxes only corporate income
This computation depends on a completed federal Form 1120. The federal return must be
finalized first; invoke tax-prep:form-1120-prep if the federal return is not yet complete.
Apportionment (Florida)
Florida uses a single sales factor for tax years beginning on or after January 1, 2019.
Prior to 2019, Florida used a three-factor formula with double-weighted sales (25% property,
25% payroll, 50% sales).
Sales factor: Florida sales / Total sales everywhere
Market-based sourcing for services: Revenue is sourced to the state where the benefit
of the service is received, not where it is performed.
No throwback rule: Sales not taxed by any other state are excluded from the Florida
numerator (unlike throwback states where they would be added back).
No combined/unitary reporting: Each corporation files separately unless electing
consolidated.
Florida NOL Rules (Florida)
Florida maintains a separate NOL carryforward schedule distinct from the federal NOL.
Florida NOL = the apportioned loss in a given year (after Florida modifications and apportionment)
Post-2017 NOLs: Indefinite carryforward, subject to 80% of Florida taxable income limitation (conforming to TCJA)
Pre-2018 NOLs: 20-year carryforward
No CARES Act carryback: Florida did not conform to the 5-year carryback for 2018-2020 NOLs
Track Florida NOLs separately from federal NOLs; invoke tax-prep:nol-tracking for the federal NOL ledger
Florida Estimated Tax (Florida)
Required when expected FL tax liability exceeds $2,500
Quarterly payments using Form F-1120ES, aligned with federal estimated payment schedule
Underpayment penalty: 12% per annum on the underpayment amount
Electronic payment required if the corporation meets the e-file mandate threshold
Filing Deadlines and Extensions
Due date: The later of the standard Florida deadline OR 15 days after the federal due date.
June 30 year-end: 4th month following close
All other year-ends: 5th month following close
Calendar-year C-corps: Federal due April 15; Florida due April 30 or May 1 (whichever is later)
Extensions: Form F-7004 grants a 6-month extension (7 months for June 30 fiscal year-ends). An extension does not extend the time to pay; tentative tax must accompany the request.
Late filing penalties:
With tax due: 10% per month (or fraction), up to 50% maximum
No tax due: $50 per month, up to $300 maximum
Non-electronic filing when required: $500 or 5% of tax due, whichever is greater
Florida IRC Conformity (Florida)
Florida piggybacks on the IRC as of January 1 of the current tax year (rolling conformity).
Key non-conformities:
No CARES Act NOL carryback
Own addback rules for related-party intangible expenses
Bonus depreciation conformity has varied by year; check the year-specific conformity date
E-Filing Requirements (Florida DOR)
E-File Mandate
Electronic filing is required if either condition is met:
Paid $5,000 or more in FL corporate income tax during the prior state fiscal year (July 1 - June 30)
Required to e-file the federal income tax return (federal threshold dropped to 10 returns in 2024 per T.D. 9972)
Filing Method: IRS MeF
The primary channel for F-1120 is the federal MeF (Modernized e-File) Fed/State program.
Federal and Florida returns can be submitted together in a single MeF transmission through
IRS- and FL DOR-approved software vendors.
Florida eServices Portal (Florida)
Used for supplemental functions: estimated tax payments (F-1120ES), extensions (F-7004),
account management, tax clearance letters. Available 24/7 Monday-Saturday; Sunday
maintenance window. Enrollment required; allow 3 business days for new application
processing.
Payment Methods
EFT/ACH (required if meeting e-file mandate): Initiate by 5:00 PM ET on the business day before due date
MeF software vendor payment
Direct enrollment with FL DOR
Credit card through authorized processors
Amended Returns
Amended F-1120 can be e-filed through MeF. If the original was required to be e-filed,
the amendment must also be e-filed.
Multistate Filing Considerations
Combined reporting: Florida does not require it. Each entity files separately.
Throwback rule: Florida has none. Nowhere sales are excluded from the FL numerator.
P.L. 86-272: Florida respects it for tangible personal property sales.
Voluntary disclosure: FL DOR offers a voluntary disclosure program reducing lookback to 3 years and waiving penalties for corporations that should have been filing.
Year-by-Year Variance Summary
For detailed year-by-year tables covering rate, exemption, apportionment formula, NOL
rules, and IRC conformity date, consult the reference files below. Key inflection points:
2012: Exemption increased from $5,000 to $50,000 (HB 7087)
2019: Single sales factor adopted (replacing three-factor double-weighted sales)
2019-2020: Rate reduced to 4.458% (TCJA revenue neutrality)
2021: Rate reduced to 3.535% (SB 50, temporary)
2022: Rate reverts to 5.5%
2024: Federal e-file threshold drops to 10 returns (T.D. 9972), triggering FL e-file mandate for more corporations
Decision Workflow: State Return Preparation
Run nexus evaluation (see Nexus Evaluation Workflow above)
For each filing state, gather: federal taxable income, state-specific additions/subtractions, apportionment factors
Compute apportioned income using the state's formula (Florida: single sales factor post-2018)
Apply state exemption ($50,000 for Florida)
Compute tax and compare to estimated payments made
Check e-file mandate and select filing method
Prepare return using approved software through MeF
File and confirm acknowledgment
Supporting References
Read these for detailed lookup tables, full year-by-year variance data, and authoritative
citations:
references/state-nexus.md — Full nexus determination framework: physical presence
tests, economic nexus thresholds (MTC factor presence standard), P.L. 86-272 analysis,
Florida corporate income tax computation walkthrough, apportionment formula details,
Florida NOL rules with year-by-year variance table (2007-2026), multistate filing
considerations. Read when performing a nexus evaluation, computing Florida taxable income,
or researching year-specific FL rules.
references/florida-e-filing.md — Florida DOR electronic filing: e-file mandate
thresholds, MeF Fed/State filing workflow, eServices portal capabilities, payment
methods and timing requirements, extension procedures (F-7004), estimated tax (F-1120ES),
amended return e-filing, penalty schedule (late filing, late payment, non-electronic
filing), account registration. Read when determining e-file obligations, setting up
electronic payments, or handling Florida DOR correspondence.
references/templates/1120-florida/ — Blank Florida Form F-1120 PDFs and corresponding
instruction PDFs organized by tax year (2007-2025). Subdirectories: blank/ contains
the form PDFs; instructions/ contains the instruction PDFs. Use these as authoritative
references for form field layout and line-by-line completion guidance for a specific tax
year. Note: Some years have variant filenames (e.g., f1120--2017-from-2016.pdf,
f1120--2020-from-2019.pdf) indicating the form was carried forward from a prior year.
Cross-Plugin References
For federal return data feeding into state computation:
Invoke tax-prep:form-1120-prep for federal taxable income (Line 30), book-tax differences, and Schedule M-1/M-3 data that determine the state starting point
Invoke tax-prep:business-tax-schema for form line definitions and cross-year line mapping when working with historical state returns
For federal and state e-filing mechanics:
Invoke tax-prep:e-filing for MeF specifications, EFIN management, rejection code resolution, and signature authorization (Form 8879-C)
Invoke tax-prep:tax-compliance for deadline management, extension filing (Form 7004), and penalty abatement strategies
For NOL and tax planning:
Invoke tax-prep:nol-tracking for the federal NOL carryforward ledger; Florida maintains a separate NOL schedule (documented in this skill)
Invoke tax-prep:tax-planning for multi-year state tax planning, estimated payment optimization, and entity structure considerations
Invoke financial-planning:tax-provision for ASC 740 state tax provision and deferred tax computations
For supporting form schedules:
Invoke tax-prep:tax-forms for supporting federal schedules that carry into state returns
For nexus and sales/use tax overlap:
Invoke bookkeeping:compliance-reporting for sales/use tax nexus analysis and state registration requirements that may share nexus triggers with income tax
For entity and account structure:
Invoke accounting-foundation:entity-profile for corporate entity details affecting state filing (domicile state, registered states, fiscal year)
Invoke accounting-foundation:chart-of-accounts for GL account mapping to state tax lines (9100s state current tax expense)
Invoke accounting-foundation:financial-statements for state-specific reporting presentation
For accounting system data extraction:
Invoke qbo-integration:qbo-reporting for pulling financial data used in apportionment factor computation (sales by state, payroll by state, property by state)
Invoke qbo-integration:qbo-audit for tax data extraction supporting state return preparation
Cross-Plugin Consumers
tax-prep:e-filing — consumes completed state returns for electronic filing transmission
tax-prep:form-1120-prep — references state tax liability for federal deduction analysis
tax-prep:tax-planning — uses state nexus analysis and rate data for multi-state planning
tax-prep:nol-tracking — coordinates federal and state NOL utilization ordering
financial-planning:tax-provision — uses state rate and apportionment data for ASC 740 provision
financial-planning:variance-analysis — uses state tax estimates for budget-to-actual variance
firm-operations:engagement-management — uses state filing list for engagement scoping
firm-operations:quality-compliance — references state filing requirements for review checklists
