Research

Business Entity Comparison 2026: LLC vs S-Corp vs C-Corp vs Partnership vs Sole Proprietorship

By The Ledgerism Editorial Team · The Ledgerism Brief Editorial Team produces original, methodology-disclosed accounting and tax research—data trackers, databases, and reference guides built to be the most-cited source in the field. Every figure is verified against primary sources including FASB, the IRS, the PCAOB, NASBA, the AICPA, and state boards of accountancy.

A data-backed comparison of the five U.S. business structures across the metrics that actually differ between them: how many file, how much income they report, how often they are audited, how fast they are growing, what industries they cluster in, and how each is taxed. Every figure below carries its exact source year and geography. All data is United States only.

A note on terminology before the numbers. “LLC” is a state-law legal status, not a federal tax classification. The IRS does not file LLCs as a separate return type. A single-member LLC is taxed by default as a sole proprietorship (Schedule C), a multi-member LLC is taxed by default as a partnership (Form 1065), and any LLC may elect to be taxed as an S corporation (Form 1120-S) or C corporation (Form 1120). This is why federal tax statistics count returns by the four federal forms, while the LLC shows up inside the partnership data. The IRS reports that LLCs have made up the majority of partnerships for more than two decades.

Executive summary

• Nonfarm sole proprietorships are the most common business structure by a wide margin, with 30,980,966 Schedule C returns filed for Tax Year 2022 (IRS SOI, November 2024).
• Partnerships filed 4,575,280 returns for Tax Year 2023, a 1.7% increase over 2022, and LLCs make up the majority of those partnerships (IRS SOI, April 2025).
• Of the 6.8 million active corporate returns filed for Tax Year 2022, pass-through entities (Forms 1120-S, 1120-REIT, 1120-RIC) accounted for 77.3% (5.3 million), leaving roughly 1.6 million traditional C-style returns (IRS SOI Publication 5655, Rev. 9-2025).
• Corporate pre-tax profit (net income less deficit) rose 17.7% to $4.8 trillion for Tax Year 2022, while corporate income tax rose 18.8% to $604.2 billion (IRS SOI Publication 5655).
• Partnership pass-through income (total income minus deductions allocated to partners) fell 17.9% to $2,099.4 billion for Tax Year 2023, down from $2,558.0 billion in 2022 (IRS SOI, April 2025).
• Audit risk is low for every structure and is lowest for pass-throughs: for Tax Year 2021, the most recent year fully outside the assessment statute, the IRS examined 0.1% of S corporation and partnership returns versus 0.4% of non-1120-S corporation returns (IRS Data Book Pub 55B, Table 3-1, FY2025).
• The Census Bureau counted 30.4 million nonemployer businesses (no paid staff) for reference year 2023, up from 29.8 million in 2022 (U.S. Census Bureau, 2025).
• The SBA Office of Advocacy counts 36,207,130 small businesses, of which 82.3% are nonemployers and 17.7% are employer firms; small businesses are 99.9% of all U.S. firms and 43.5% of GDP (SBA Office of Advocacy FAQ, February 2026).

Key findings

1. Nonfarm sole proprietorships filed 30,980,966 returns for Tax Year 2022, a 5.7% increase from 2021, representing an estimated 35,255,144 businesses (IRS SOI, Sole Proprietorship Returns Tax Year 2022, November 2024).
2. Sole proprietorship profits fell 0.2% to $410.7 billion for Tax Year 2022, and profit as a share of business receipts dropped to 19.7%, the lowest level since 1990 (IRS SOI, November 2024).
3. Partnerships filed 4,575,280 returns for Tax Year 2023 and represented more than 30.2 million partners (IRS SOI, Partnership Returns Tax Year 2023, April 2025).
4. The number of partnerships grew at an average annual rate of 2.9% over 2014 to 2023 (IRS SOI, April 2025).
5. Limited partnerships were 9.7% of all partnerships in Tax Year 2023 while LLCs were the majority, the dominant entity type among partnerships for over twenty years (IRS SOI, April 2025).
6. The real estate and rental and leasing sector comprised 50.7% of all partnerships and 32.8% of all partners for Tax Year 2023 (IRS SOI, April 2025).
7. There were 6.8 million active corporate income tax returns filed for Tax Year 2022, of which 93.8% (6.4 million) were filed electronically (IRS SOI Publication 5655, Rev. 9-2025).
8. Pass-through corporate returns (1120-S, 1120-REIT, 1120-RIC) were 77.3% of all active corporate returns for Tax Year 2022, about 5.3 million returns (IRS SOI Publication 5655).
9. Corporate net income (less deficit) rose 17.7% to $4.8 trillion for Tax Year 2022, and corporate income tax rose 18.8% to $604.2 billion (IRS SOI Publication 5655).
10. Of roughly 1.6 million non-pass-through (C-type) corporate returns for Tax Year 2022, about 739,000 reported net income and 82.1% of those had a tax liability (IRS SOI Publication 5655).
11. For Tax Year 2021, the IRS examined 0.4% of corporation returns other than Form 1120-S, 0.1% of S corporation returns, and 0.1% of partnership returns (IRS Data Book Pub 55B, Table 3-1, FY2025).
12. For Tax Year 2021, individual return examination coverage rose from 0.2% in the $1 to $25,000 income band to 5.2% for returns reporting $10 million or more of total positive income (IRS Data Book Pub 55B, Table 3-1, FY2025).
13. The Census Bureau counted 30.4 million nonemployer businesses with $1.8 trillion in receipts for reference year 2023 (U.S. Census Bureau, 2025).
14. The number of nonemployer firms nearly doubled from 15.4 million in 1997 to 29.8 million in 2022 (SBA Office of Advocacy FAQ, February 2026).
15. Small businesses (fewer than 500 employees) account for 99.9% of all U.S. firms, 45.9% of private-sector employees (62.3 million workers), and 43.5% of GDP (SBA Office of Advocacy FAQ, February 2026).

Section 1: How many of each entity type file

The clearest way to compare entity popularity is to count federal returns. The two relevant IRS sources measure slightly different things and are not directly additive. The Statistics of Income (SOI) studies count returns filed for a given tax year (sampled and weighted). The IRS Data Book counts returns and forms processed during a federal fiscal year, which includes prior-year and late filings. Both are shown so the difference is explicit.

LLCs do not appear as a row in either source because they are a state-law form, not a federal return type. The default federal treatment places single-member LLCs inside the Schedule C (sole proprietorship) count and multi-member LLCs inside the Form 1065 (partnership) count, with the IRS confirming LLCs are the majority of partnerships.

Returns filed by federal form

The SOI corporate one-pager reports 6.8 million total active corporate returns for Tax Year 2022, with pass-throughs (1120-S, 1120-REIT, 1120-RIC) at 77.3% (5.3 million) and roughly 1.6 million non-pass-through (C-type) returns. That reconciles with the Data Book TY2022 split above (about 5.27 million 1120-S plus about 1.56 million other 1120-series).

Returns and forms processed by fiscal year (IRS Data Book Table 1-2)

Source: IRS Data Book, Publication 55B, Table 1-2, Fiscal Years 2024 and 2025.

The fiscal-year processed counts run higher than the tax-year filed counts (for example, 6.08 million 1120-S processed in FY2024 versus 5.27 million filed for TY2022) because a single fiscal year processes returns from multiple tax years plus extensions and amendments. Use the SOI tax-year figures for “how many businesses of this type exist for year X” and the Data Book fiscal-year figures for “how much filing volume the IRS handled.”

What the counts mean: sole proprietorships outnumber every incorporated and partnership structure combined by roughly six to one. S corporations now file more returns than C-type corporations, a structural fact that reflects decades of pass-through election. Partnerships, which carry most multi-member LLCs, are the fastest-growing of the entity returns on a percentage basis in the SOI series.

Section 2: Income reported by each structure

No single official table reports net income for all five structures in one year, and the measures are not defined identically (corporate “net income less deficit” is pre-tax book-tax profit; partnership “pass-through income” is income minus deductions allocated to partners; sole proprietor “profit” is Schedule C net profit). They are presented separately with their definitions so they are not falsely equated.

Corporate income tax for Tax Year 2022 was $604.2 billion (up 18.8%), and total income tax after credits, the amount actually paid to the Treasury, was $448.7 billion (up 20.8%) (IRS SOI Pub 5655). Partnerships and S corporations generally pay no entity-level federal income tax; they pass income through to owners, which is why the Data Book reports no corporate-style tax liability for those forms.

Sole proprietorship receipts were $2,080.7 billion for Tax Year 2022, up 11.4% from $1,868.0 billion in 2021, but profit margin compressed: profit as a share of receipts fell to 19.7%, the lowest since 1990 (IRS SOI, Nov 2024). Partnership pass-through income fell 17.9% year over year, with the real estate and rental and leasing sector accounting for the largest single decrease ($294.4 billion) (IRS SOI, Apr 2025).

Section 3: Audit risk by entity type

Audit risk is one of the most cited reasons taxpayers ask about entity choice, and the data show the differences are real but small in absolute terms. The critical methodological caveat from the IRS itself: examination coverage for recent tax years understates the eventual audit rate because the assessment statute (generally three years) is still open and more audits will be opened. The IRS states that Tax Year 2021 is the most recent tax year fully outside the normal statute period, so TY2021 is the most reliable year for comparison. Coverage shown for TY2022 and TY2023 is incomplete and will rise.

Examination coverage by return type (percent of returns filed examined)

* denotes less than 0.05% or not yet meaningful at this snapshot. Source: IRS Data Book, Publication 55B, Table 3-1, FY2025.

Individual returns are not a single rate. For Tax Year 2023 (a snapshot that will rise), examination coverage ranged from about 0.1% in middle-income bands up to 2.0% at $5 million to $10 million of total positive income and 5.2% at $10 million or more (IRS Data Book Pub 55B, Table 3-1). Because Schedule C sole proprietor income is reported on the Form 1040, sole proprietors face individual examination coverage that rises sharply with total income rather than a flat business audit rate.

What the numbers mean: for Tax Year 2021, a C-style corporation was roughly four times as likely to be examined as an S corporation or partnership (0.4% versus 0.1%), but even the highest entity rate is well under 1%. The very low pass-through entity-level rates do not capture audits that occur at the owner level, since partnership and S corporation income flows onto owners’ individual returns.

Section 4: Popularity and growth over time

Two long-run signals are reliable. First, the shift toward pass-throughs: S corporations now file more returns than C-type corporations, and LLCs (filing as partnerships or disregarded sole proprietorships) have been the majority partnership type for over two decades (IRS SOI). Second, the rise of the smallest businesses: the Census Bureau and SBA both document rapid nonemployer growth.

The Census Bureau notes that the number of U.S. nonemployers grew faster than employer businesses in nearly every year from 2012 to 2023, and the total rose from 24 million in 2015 to 30 million in 2023, a 25% increase (U.S. Census Bureau, 2025). Important data caveat: Census changed its nonemployer receipts cutoffs starting with reference year 2022, so 2022-and-later counts are not strictly comparable to earlier years.

Section 5: Industry mix

Industry concentration differs sharply by structure, which matters for anyone using these structures as a proxy for an industry. Partnership data is the most concentrated: the real estate and rental and leasing sector was 50.7% of all partnerships for Tax Year 2023 (IRS SOI, Apr 2025). The finance and insurance sector dominated partnership assets, receipts, and total income for Tax Year 2023 (IRS SOI, Apr 2025).

For nonemployer businesses (overwhelmingly sole proprietorships), the largest 2022 sectors by establishment count were Professional, Scientific, and Technical Services (4,013,209), Transportation and Warehousing (3,854,720), and Real Estate, Rental and Leasing (3,145,367) (U.S. Census Bureau, 2024). Real Estate, Rental and Leasing had the largest nonemployer receipts in 2022 at $344.7 billion, 20.0% of the total (U.S. Census Bureau, 2024).

For sole proprietorships filing Schedule C in Tax Year 2022, the professional, scientific, and technical services sector held the largest share of profits at 24.7% ($101.6 billion), and the construction sector reported the largest share of total business receipts at 18.1% (IRS SOI, Nov 2024).

Section 6: Tax treatment of each structure (stated neutrally)

The following describes the default federal tax treatment of each structure as a matter of fact. It is not tax advice and omits state taxes, which vary. Sources are the relevant IRS form instructions and SOI definitions.

Source: IRS form instructions for Forms 1040 Schedule C, 1065, 1120, 1120-S; IRS SOI study definitions. The defining federal distinction is the number of taxation layers: the C corporation is the only structure taxed at the entity level and again on distributions; the other four are single-layer pass-throughs by default. The S corporation and C corporation differ in tax mechanics, not legal form, and an LLC can elect either.

Original synthesis

Insight 1: Pass-through dominance ratio

Logic: divide pass-through corporate returns by total active corporate returns for the same tax year. For Tax Year 2022, that is 5.3 million / 6.8 million = 77.3% (the figure the IRS reports directly). Adding the 4,575,280 partnerships (TY2023) and 30,980,966 sole proprietorships (TY2022), pass-through structures account for the overwhelming majority of all U.S. business returns; only the roughly 1.6 million non-pass-through C-type corporate returns sit outside the pass-through universe. Inputs: IRS SOI Pub 5655 (TY2022 corporate), IRS SOI partnership (TY2023), IRS SOI sole proprietorship (TY2022). Limitation: the three counts are from two different tax years (2022 and 2023) and cannot be summed into a single-year total; they establish magnitude, not a precise universe.

Insight 2: Relative audit-risk index (Tax Year 2021, statute-closed)

Logic: index each entity’s TY2021 examination coverage to the lowest-risk pass-through (S corporation and partnership at 0.1% = baseline 1.0). C-type corporations at 0.4% index to 4.0. Individual returns are scale-dependent: the $10 million-plus band at 5.2% indexes to roughly 52 relative to the pass-through baseline. Result: among entity returns, a C-type corporation carried about four times the entity-level examination probability of a pass-through for TY2021, but high-income individual returns (which capture large sole proprietors) carried by far the highest probability. Inputs: IRS Data Book Pub 55B, Table 3-1. Limitation: entity-level rates exclude owner-level audits of pass-through income; the index compares examination probability, not audit severity or recommended tax.

Insight 3: Growth-rate divergence (smallest businesses vs incorporated)

Logic: compare the compound trajectories. Nonemployer businesses rose from 24 million (2015) to 30.4 million (2023), about +27% over eight years, while the Census reports nonemployers grew faster than employer businesses in nearly every year from 2012 to 2023. Partnerships grew at a 2.9% average annual rate (2014-2023). Sole proprietorship returns rose 5.7% in a single year (TY2021 to TY2022). The structural story is concentration at the smallest end. Inputs: U.S. Census Bureau (2025), IRS SOI (2024-2025). Limitation: the Census 2022 cutoff change overstates measured growth into 2022; nonemployer and Schedule C universes overlap heavily but are not identical.

Charts to create

1. Title: “U.S. business returns by structure, most recent SOI year.” Data: 30.98M sole prop (TY2022), 5.27M S corp (TY2022), 4.58M partnership (TY2023), 1.56M C-type (TY2022). Source: IRS SOI. Insight: sole proprietorships dwarf all incorporated and partnership forms. Citation-worthy because it visually settles the “most common entity” question with primary data.
2. Title: “Entity examination coverage, Tax Year 2021 (statute-closed).” Data: C-type 0.4%, S corp 0.1%, partnership 0.1%, individual by income band 0.1% to 5.2%. Source: IRS Data Book Table 3-1. Insight: audit risk is low everywhere and concentrated at high individual income. Citation-worthy because it corrects the common overstatement of small-business audit risk.
3. Title: “Nonemployer business growth, 1997-2023.” Data: 15.4M (1997), 29.8M (2022), 30.4M (2023). Source: SBA Office of Advocacy, U.S. Census Bureau. Insight: the smallest businesses nearly doubled in 25 years. Citation-worthy as the clearest long-run growth signal for sole proprietors.
4. Title: “Income by structure with definitions.” Data: corporate net income $4.8T (TY2022), partnership pass-through $2.10T (TY2023), sole prop profit $0.41T (TY2022). Source: IRS SOI. Insight: corporate income is an order of magnitude larger than sole proprietor profit. Citation-worthy if the differing definitions are labeled on the chart.
5. Title: “Pass-through share of corporate returns, Tax Year 2022.” Data: 77.3% pass-through vs 22.7% non-pass-through. Source: IRS SOI Pub 5655. Insight: the corporate return universe is now mostly S corporations and other pass-throughs.

Methodology

Source selection prioritized Tier-1 primary federal statistics: IRS Statistics of Income (SOI) annual studies for entity counts and income, the IRS Data Book (Publication 55B) for filing volumes and examination coverage, the U.S. Census Bureau Nonemployer Statistics for employer-versus-nonemployer firm counts, and the SBA Office of Advocacy for the small-business aggregate picture. Secondary sources were used only to locate primary documents and were not cited for figures.

Inclusion rule: a statistic appears only if it was confirmed in a primary federal document with an explicit reference year. Exclusion rule: any figure that could not be tied to a named year and source was dropped. Conflicting-number handling: the IRS reports business counts two ways (SOI tax-year filed counts and Data Book fiscal-year processed counts); both are shown and the difference is explained rather than blended. The five income measures are reported under their own definitions and explicitly not summed.

Derived figures: the pass-through dominance ratio (Insight 1) uses the IRS-reported 77.3% directly and contextualizes it with partnership and sole-proprietor counts. The audit-risk index (Insight 2) normalizes Table 3-1 coverage to the pass-through baseline. No projections or estimates are presented as current. Data limitations: SOI income data lags to TY2022 (corporations, sole proprietors) and TY2023 (partnerships); examination coverage for TY2022-2023 is incomplete because the assessment statute is open; the integrated cross-entity SOI series ends at 2015; the Census 2022 nonemployer cutoff change breaks comparability with pre-2022 years. Date of last update: 2026-06-29.

Source quality ranking

Tier 1 (primary government statistics):
– IRS Statistics of Income, Corporate Income Tax Returns Tax Year 2022 (Publication 5655, Rev. 9-2025).
– IRS Statistics of Income, Partnership Returns Tax Year 2023 (April 2025).
– IRS Statistics of Income, Sole Proprietorship Returns Tax Year 2022 (November 2024).
– IRS Data Book, Publication 55B (FY2025 edition), Tables 1-2 and 3-1.
– U.S. Census Bureau, Nonemployer Statistics, reference years 2022 and 2023.
– SBA Office of Advocacy, Frequently Asked Questions About Small Business (February 2026), drawing on SUSB, NES, and Advocacy data.

Tier 2 / Tier 3: none relied upon for figures. Excluded: the IRS Integrated Business Data series (a true cross-entity comparison) was reviewed but not used for current figures because it ends at reference year 2015 and would have presented stale data as current. Third-party tax-advisory summaries were excluded because they restate IRS data without adding verifiable primary detail.

Citation format

• Source: IRS, Statistics of Income Division, Corporate Income Tax Returns Tax Year 2022, Publication 5655 (Rev. 9-2025).
• Source: IRS, Statistics of Income Division, Partnership Returns Tax Year 2023, April 2025.
• Source: IRS, Statistics of Income Division, Sole Proprietorship Returns Tax Year 2022, November 2024.
• Source: IRS Data Book, Publication 55B, FY2025, Table 3-1 (Examination Coverage) and Table 1-2 (Returns Filed).
• Source: U.S. Census Bureau, Nonemployer Statistics, reference year 2023 (released 2025).
• Source: SBA Office of Advocacy, Frequently Asked Questions About Small Business, February 2026.

Journalist-friendly additions

Most quotable statistics

• “Sole proprietorships are by far the most common U.S. business structure, with 30,980,966 Schedule C returns filed for Tax Year 2022.” (IRS SOI, Nov 2024)
• “S corporations now file more federal returns than traditional C-style corporations; pass-throughs were 77.3% of all corporate returns for Tax Year 2022.” (IRS SOI Pub 5655)
• “Even the most-audited business entity is examined less than half a percent of the time: C-type corporations had a 0.4% examination rate for Tax Year 2021, versus 0.1% for S corporations and partnerships.” (IRS Data Book Table 3-1)
• “Corporate pre-tax profit hit $4.8 trillion for Tax Year 2022, up 17.7%.” (IRS SOI Pub 5655)
• “Small businesses are 99.9% of all U.S. firms and 43.5% of GDP.” (SBA Office of Advocacy, Feb 2026)

Data limitations

IRS income statistics lag one to two years and differ by tax year across entity types (corporations and sole proprietors to TY2022; partnerships to TY2023), so cross-entity income comparisons mix years. Examination coverage for the two most recent tax years is incomplete and will rise as the statute stays open; only Tax Year 2021 is fully comparable. The five income measures use different definitions and must not be summed. Census nonemployer counts changed methodology in 2022, breaking the pre-2022 trend line. LLCs are not a federal return type and are embedded in the partnership and sole-proprietor counts.

Downloadable dataset, recommended fields

structure, federal_form, metric (returns_filed / net_income / examination_coverage / industry_share), value, unit, tax_year_or_period, geography (United States), source_organization, source_publication, source_year, methodology_note, comparability_flag, source_url.

Press summary (150 words)

A 2026 comparison of the five U.S. business structures, built entirely on primary federal data, shows that sole proprietorships remain dominant by count, with 30,980,966 Schedule C returns filed for Tax Year 2022, while partnerships filed 4,575,280 returns for Tax Year 2023 and pass-through corporations made up 77.3% of all 6.8 million corporate returns for Tax Year 2022. Corporate pre-tax profit reached $4.8 trillion for Tax Year 2022. Audit risk is low and concentrated: for Tax Year 2021, the IRS examined 0.4% of C-type corporate returns and 0.1% of S corporation and partnership returns, with individual coverage rising to 5.2% above $10 million of income. The smallest businesses are growing fastest, with nonemployer firms reaching 30.4 million in 2023. The defining tax distinction is layers of taxation: the C corporation is taxed at the entity and again on dividends, while the other four structures are single-layer pass-throughs by default.

Suggested headlines

1. Sole Proprietors Still Rule: 31 Million Schedule C Filers Dwarf Every Other Business Structure
2. Pass-Throughs Now 77% of Corporate Returns as S Corps Overtake C Corps
3. The Real Audit Numbers: No Business Entity Is Examined More Than 0.4%
4. LLC vs S-Corp vs C-Corp: What the IRS Data Actually Shows in 2026
5. Corporate Profit Hit $4.8 Trillion in 2022 While Sole Proprietor Margins Fell to a 32-Year Low

FAQs

1. What is the most common business structure in the U.S.? The nonfarm sole proprietorship, with 30,980,966 Schedule C returns filed for Tax Year 2022 (IRS SOI, Nov 2024).
2. Do more businesses file as S corporations or C corporations? S corporations file more returns; for Tax Year 2022 the Data Book recorded about 5.27 million 1120-S returns versus about 1.56 million other 1120-series returns (IRS Data Book Table 3-1).
3. Is an LLC a separate tax entity? No. An LLC is a state-law status taxed by default as a sole proprietorship (single-member) or partnership (multi-member), and it may elect S or C corporation treatment (IRS form instructions).
4. Which entity gets audited most? Among entity returns, C-type corporations, at 0.4% examination coverage for Tax Year 2021, versus 0.1% for S corporations and partnerships (IRS Data Book Table 3-1).
5. How much do sole proprietors earn? Nonfarm sole proprietorships reported $410.7 billion in profit for Tax Year 2022, down 0.2% from 2021 (IRS SOI, Nov 2024).
6. How much pass-through income do partnerships generate? Partnerships passed through $2,099.4 billion to partners for Tax Year 2023, down 17.9% from $2,558.0 billion in 2022 (IRS SOI, Apr 2025).
7. How large is corporate income? Corporate net income (less deficit) was $4.8 trillion for Tax Year 2022 (IRS SOI Pub 5655).
8. How many small businesses are there? The SBA Office of Advocacy counts 36,207,130, of which 82.3% are nonemployers (SBA, Feb 2026).
9. Which industries use partnerships most? Real estate and rental and leasing, at 50.7% of all partnerships for Tax Year 2023 (IRS SOI, Apr 2025).
10. Why can’t the income figures be added together? They come from different tax years (2022 and 2023) and use different definitions (corporate pre-tax net income, partnership allocated pass-through income, sole-proprietor Schedule C profit), so summing them would misstate the total (IRS SOI study definitions).

Sources

1. IRS, Statistics of Income, Corporate Income Tax Returns Tax Year 2022, Publication 5655 (Rev. 9-2025). https://www.irs.gov/pub/irs-pdf/p5655.pdf
2. IRS, Statistics of Income, Partnership Returns Tax Year 2023 (April 2025). https://www.irs.gov/pub/irs-soi/soi-a-copa-id2505.pdf
3. IRS, Statistics of Income, Sole Proprietorship Returns Tax Year 2022 (November 2024). https://www.irs.gov/pub/irs-soi/soi-a-insp-id2502.pdf
4. IRS Data Book, Publication 55B (FY2025 edition), Tables 1-2 and 3-1. https://www.irs.gov/pub/irs-pdf/p55b.pdf
5. IRS, SOI Tax Stats, Examination Coverage, IRS Data Book Table 17 / Table 3-1. https://www.irs.gov/statistics/soi-tax-stats-2023-irs-data-book-table-17-revised
6. IRS, SOI Tax Stats, Partnership statistics by entity type (Table 9a). https://www.irs.gov/statistics/soi-tax-stats-partnership-statistics-by-entity-type
7. IRS, SOI Tax Stats, Nonfarm sole proprietorship statistics. https://www.irs.gov/statistics/soi-tax-stats-nonfarm-sole-proprietorship-statistics
8. U.S. Census Bureau, Census Bureau Releases 2023 Nonemployer Statistics (2025). https://www.census.gov/newsroom/press-releases/2025/2023-nonemployer-statistics.html
9. U.S. Census Bureau, Census Bureau Releases 2022 Nonemployer Statistics (2024). https://www.census.gov/newsroom/press-releases/2024/2022-nonemployer-statistics.html
10. U.S. Census Bureau, Number of U.S. Nonemployers Grew Faster Than Employer Businesses (2025). https://www.census.gov/library/stories/2025/07/nonemployer-business-growth.html
11. SBA Office of Advocacy, Frequently Asked Questions About Small Business (February 2026). https://advocacy.sba.gov/wp-content/uploads/2026/02/FINAL_FAQsAboutSmallBusiness_2026_012826.pdf
12. IRS, SOI Tax Stats, Integrated Business Data (1980-2015, reviewed, excluded as stale). https://www.irs.gov/statistics/soi-tax-stats-integrated-business-data

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