Common Law Test (Worker Classification)

The Common Law Test is the federal worker classification standard the Internal Revenue Service uses to decide whether a worker is an employee or an independent contractor for purposes of federal income tax withholding, the Federal Insurance Contributions Act (FICA), and the Federal Unemployment Tax Act (FUTA). The test is grounded in the common-law master-servant doctrine, refined through court decisions, and restated by the IRS in Publication 15-A, Employer’s Supplemental Tax Guide and in Topic No. 762, Independent contractor vs. employee. The IRS organizes the analysis into three categories of evidence: behavioral control, financial control, and the relationship of the parties.

The Three Categories

Category	What It Examines
Behavioral control	Whether the business has the right to direct and control how the worker performs the work, including instructions, training, and supervision
Financial control	Whether the business controls the economic aspects of the worker’s job, including unreimbursed expenses, investment in tools, payment method, and the worker’s ability to realize a profit or loss
Relationship of the parties	How the parties characterize and structure the relationship, including written contracts, employee-type benefits, permanence of the engagement, and whether the services are a key aspect of the business

The categories are factors, not requirements. No single factor controls the outcome. The IRS evaluates the totality of the circumstances and assigns weight to each factor based on the occupation and the specific facts.

Origin and Authority

The IRS Common Law Test traces back to the master-servant doctrine in agency law, which courts adapted to federal employment tax disputes. The modern IRS framework was consolidated in Revenue Ruling 87-41, which compiled twenty common-law factors from federal court decisions into the structure now known as the IRS 20-Factor Test. The 20 factors have since been folded into the three modern categories used in Publication 15-A and Topic 762, but the underlying common-law analysis is the same.

For a definition of “employee” for federal employment tax purposes, the IRS relies on the common-law definition set out in Treasury Regulation Section 31.3121(d)-1, which describes the master-servant relationship as the central inquiry.

When the Common Law Test Applies

The Common Law Test governs federal employment tax determinations:

• Federal income tax withholding under Internal Revenue Code Subtitle C
• FICA contributions (Social Security and Medicare), both employer and employee shares
• FUTA contributions for federal unemployment

The Common Law Test does not control state classification questions. State unemployment insurance and state wage-and-hour systems often apply the ABC Test or a state-specific control test. The federal Fair Labor Standards Act applies the Economic Reality Test administered by the US Department of Labor, which examines economic dependence rather than control alone. A worker can be a contractor for federal tax purposes and an employee for state wage purposes at the same time.

Common Law Test vs ABC Test

Aspect	Common Law Test (IRS)	ABC Test (state)
Authority	IRS, federal tax law	State statutes such as Cal. Lab. Code 2775 and Mass. G.L. c. 149, s. 148B
Presumption	None, multi-factor balancing	Worker is presumed an employee
Burden of proof	On the IRS to establish employee status	On the hiring entity to defeat the presumption by satisfying all three prongs
Outcome turns on	Right to control the work	Three independent prongs (control, outside usual course, independent business)
Scope	Federal income tax, FICA, FUTA	State unemployment insurance and, in some states, wage-and-hour law

The Common Law Test is more flexible than the ABC Test. The ABC Test is generally easier for state agencies to apply and harder for hiring entities to satisfy, because failure on any one of the three prongs is dispositive.

How a Determination Is Made

Either the worker or the hiring entity can request a formal IRS determination by filing Form SS-8, Determination of Worker Status for Purposes of Federal Employment Taxes and Income Tax Withholding. The IRS reviews the facts under the three categories and issues a written determination. Processing usually takes several months. The determination binds the IRS for the specific facts presented but is informational guidance for the parties going forward.

A worker who believes a hiring entity has misclassified them can use Form 8919, Uncollected Social Security and Medicare Tax on Wages to report and pay their share of FICA on income that was reported on a 1099 instead of a W-2.

Why the Common Law Test Matters for US Companies

For US companies engaging contractors, the Common Law Test sets the federal employment tax baseline. A finding of misclassification produces back income tax withholding, both halves of FICA, FUTA, interest, and penalties. The Section 530 safe harbor can limit some of that exposure where the company can show reasonable basis and consistent treatment, but it does not change the underlying classification analysis. The Common Law Test also drives the federal contractor reporting flow on Form 1099-NEC and the employee flow on Form W-2.

How Omnivoo Helps

Omnivoo Contract Management captures the three IRS categories of evidence at the start of each contractor engagement: who controls the how, who bears the financial risk, and how the relationship is structured. The platform stores that record alongside the executed contract so the supporting common-law analysis is available if the IRS or a state agency reviews the file.