NAICS 561611 Quarterly Industry Report
Investigation Services
Comprehensive industry research for valuation professionals, business owners, buyers, and lenders
NAICS Code: 561611Sector: Administrative and Support and Waste Management and Remediation Services (56)Updated: Q1 2026
About This Report
This industry profile for Investigation Services (NAICS 561611) draws on data from the Bureau of Labor Statistics[6], U.S. Census Bureau, and SBA size standards database[7]. Published by Fair Market Value and updated quarterly, it provides valuation professionals, security consultants, and business brokers with current market data. The editorial analysis reflects the independent assessment of FairMarketValue.com's research team, with all quantitative claims sourced to publicly verifiable databases.
Industry Snapshot
Key metrics for the investigation services industry.
Share of Administrative and Support and Waste Management and Remediation Services
0.9%
By establishment count, 2022 Census[2]
NAICS Sector
56
Administrative and Support and Waste Management and Remediation Services
Industry Definition & Overview
Investigation Services (NAICS 561611) encompasses establishments primarily engaged in providing detective, guard, and private investigation services, as well as personal background check services for clients across business, government, and individual sectors per the U.S. Census Bureau[5]. Firms conduct surveillance, verify employment history, screen candidates for security clearances, and investigate theft and fraud cases.
Demand comes from multiple directions. Corporate due diligence, pre-employment screening, insurance fraud investigation, and litigation support represent core revenue streams. Regulatory requirements continue to expand the market; employers in healthcare, financial services, and government increasingly mandate thorough background verification. Most firms are small, with solo practitioners and boutique agencies outnumbering large national operations per the Bureau of Labor Statistics[6].
Technology adoption has reshaped the field. Database-driven background verification, digital forensics, and open-source intelligence tools have replaced much of the traditional legwork. Licensing requirements vary by state; most jurisdictions mandate criminal background checks, training hours, bonding, and examinations for private investigators. Per the SBA Table of Size Standards[7], the size standard is $25.0 million in average annual receipts. Geographic concentration follows population density, with California, Texas, Florida, and New York hosting the largest number of licensed investigators. Cybersecurity incidents and data breach response have created a growing sub-specialty, with firms offering digital evidence preservation and chain-of-custody documentation for civil and criminal proceedings.
What's Included in This Industry
- Private investigation and detective services
- Background check and personal screening services
- Fraud and theft investigation
- Digital forensics and computer investigation
- Surveillance and monitoring services
- Employment history verification
- Due diligence investigations for M&A transactions
- Polygraph and lie detection services
- Security clearance investigations
- Litigation support and evidence gathering
NAICS Classification Hierarchy
| Level | Description | Code |
|---|---|---|
| Sector | Administrative and Support and Waste Management and Remediation Services | 56 |
| Subsector | Administrative and Support Services | 561 |
| Industry Group | Investigation and Security Services | 5616 |
| NAICS Industry | Investigation, Guard, and Armored Car Services | 56161 |
| National Industry | Investigation and Personal Background Check Services | 561611 |
Related NAICS Codes
| Code | Description | Relationship |
|---|---|---|
| 561612 | Security Guards and Patrol Services | Security Guards and Patrol Services provide on-site physical protection, while investigation services conduct off-site information gathering, background verification, and forensic analysis |
| 561613 | Armored Car Services | Armored Car Services transport and protect valuables in transit, while investigation services examine financial crimes and fraud related to asset movement and theft |
| 561621 | Security Systems Services (except Locksmiths) | Security Systems Services install and monitor alarm systems, providing electronic surveillance that complements the human intelligence gathering of investigation firms |
| 541611 | Administrative Management and General Management Consulting Services | Administrative Management Consulting provides organizational risk assessment that may trigger investigation engagements for due diligence, fraud detection, or compliance verification |
| 541690 | Other Scientific and Technical Consulting Services | Other Scientific and Technical Consulting includes forensic consulting and expert witness services that overlap with the analytical functions of investigation firms |
| 922110 | Courts | Courts and law enforcement agencies generate demand for private investigation through litigation discovery, bail enforcement, and cases requiring private sector expertise |
Geographic Concentration
Top states by share of national establishments.
| # | State | % Est. | Total Est. |
|---|---|---|---|
| 1 | California | 16.0% | 652 |
| 2 | Florida | 12.6% | 516 |
| 3 | New York | 7.9% | 323 |
| 4 | Texas | 7.3% | 300 |
| 5 | Georgia | 3.6% | 149 |
| 6 | Illinois | 3.6% | 148 |
| 7 | Pennsylvania | 2.7% | 110 |
| 8 | Virginia | 2.6% | 108 |
| 9 | Ohio | 2.6% | 106 |
| 10 | New Jersey | 2.6% | 105 |
% Of Establishments
0%
16%
Source: County Business Patterns, U.S. Census Bureau[3]
SBA Lending Summary
256
Total SBA Loans
$48.8M
Total Loan Volume
$191K
Average Loan Size
10 yrs
Average Loan Term
10.89%
Average Interest Rate
3,504
Jobs Supported
Source: SBA 7(a) Program Data, U.S. Small Business Administration — FY 2025[4]
Key Insight: Per the SBA Table of Size Standards[7], Investigation Services (NAICS 561611) has a size standard of $25.0 million in average annual receipts for federal contracting purposes. SBA 7(a) loans[8] support technology investments, equipment purchases, and working capital for qualifying firms. Most investigation firms fall well below this threshold, making them eligible for small business contracting set-asides and SBA financing programs. Additionally, 504/CDC loans[9] provide long-term, fixed-rate financing for major fixed assets such as real estate and equipment.
Top SBA Lenders
| # | Lender | Loans | Volume | Avg Loan |
|---|---|---|---|---|
| 1 | Northeast Bank | 64 | $11.9M | $186K |
| 2 | First Internet Bank of Indiana | 16 | $11.9M | $743K |
| 3 | Newtek Bank, National Association | 24 | $4.4M | $184K |
| 4 | BayFirst National Bank | 32 | $4.2M | $131K |
| 5 | BMO Bank National Association | 8 | $3.9M | $491K |
Frequently Asked Questions
Common questions about this industry.
What types of businesses operate as investigation services?
Firms range from solo private investigators to national agencies with hundreds of employees. Specializations include corporate due diligence, insurance fraud, digital forensics, background screening, and litigation support per the U.S. Census Bureau[5]. Most firms are small operations serving local or regional markets.
How is the investigation services industry structured?
The market is highly fragmented with thousands of small firms per the Bureau of Labor Statistics[6]. Revenue comes from hourly fees, per-project pricing, and retainer arrangements. Corporate background screening represents the largest volume segment, while complex fraud investigations command premium rates.
What is the SBA size standard for Investigation Services?
Per the SBA Table of Size Standards[7], NAICS 561611 has a size standard of $25.0 million in average annual receipts. This determines eligibility for SBA loans, federal contracting set-asides, and small business programs.
What NAICS codes are related to investigation services?
Related codes include NAICS 561612 (Security Guards), NAICS 561613 (Armored Car Services), NAICS 561621 (Security Systems), NAICS 541690 (Other Technical Consulting), and NAICS 922110 (Courts) per the U.S. Census Bureau[5]. Each involves complementary security or enforcement functions.
Which industries hire investigation services most?
Insurance companies, law firms, banks, healthcare providers, and corporate HR departments generate the most demand. Pre-employment screening, insurance fraud, litigation support, and regulatory compliance drive recurring revenue from these sectors.
What activities are included in NAICS 561611?
Core activities include private detective work, background checks, employment verification, fraud investigation, surveillance, digital forensics, polygraph services, and litigation support per the U.S. Census Bureau[5]. Security clearance investigations for government contractors are also included.
Can investigation firms get SBA loans?
Yes, firms meeting the $25.0 million size standard qualify for SBA 7(a) loans[8] covering technology, equipment, marketing, and working capital. SBA financing supports both startup investigators and established firms expanding into new service areas.
Which states have the highest concentration of investigation services?
California, Texas, Florida, and New York lead in licensed investigators and firm counts per the Bureau of Labor Statistics[6]. Metropolitan areas with large corporate, legal, and insurance sectors drive the densest concentration of investigation firms.
Sources & References
Government datasets and editorial sources used in this report.
- [1]U.S. Bureau of Labor Statistics, Quarterly Census of Employment and Wages bls.gov
- [2]U.S. Census Bureau, Economic Census census.gov
- [3]U.S. Census Bureau, County Business Patterns census.gov
- [4]U.S. Small Business Administration, SBA 7(a) Loan Program Data data.sba.gov
- [5]U.S. Census Bureau census.gov
- [6]Bureau of Labor Statistics bls.gov
- [7]SBA Table of Size Standards sba.gov
- [8]SBA 7(a) loans sba.gov
- [9]504/CDC loans sba.gov
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