Overview: Health insurance is sold through two fundamentally different structures — individual and group — each with distinct contract mechanics, underwriting approaches, and regulatory rules.

Contract Structure

The most foundational structural difference is who holds the contract. In individual health insurance, the insurance company issues a policy directly to the person applying for coverage. That individual is the policyholder, and the contract is a direct legal relationship between the two parties.

In group health insurance, the insurer issues a single master policy to the sponsoring organization — typically an employer, but also associations, unions, or other groups. Individual members of the group (employees and their dependents) are not parties to the master policy. Instead, each covered member receives a certificate of insurance (or certificate of coverage) that summarizes their benefits and rights under the master policy. This distinction has real consequences: if a dispute arises, the master policy governs, not the certificate.

Underwriting and Eligibility

Underwriting — the process of evaluating risk to determine coverage and price — works very differently in the two markets.

In group insurance, underwriters evaluate the group as a whole, not each individual member. They look at factors like the employer's industry, the average age of employees, group size, and (for large groups) the group's prior claims history. The group's formation is incidental to insurance purposes; employees join because they work there, not because they are all sick and seeking coverage. This makes the risk pool relatively balanced and minimizes adverse selection. Under the Affordable Care Act (ACA), group plans are guaranteed issue — insurers must accept all eligible group members regardless of their individual health status, and they cannot charge any employee a higher premium because of personal medical history.

Individual policies are evaluated on an individual basis. For ACA-compliant individual plans sold in the major medical market, medical underwriting is prohibited — carriers cannot deny coverage or charge more because of a pre-existing condition. However, premiums can vary based on age (within a 3:1 ratio), geographic location, family size, and tobacco use. Non-ACA-compliant plans (such as short-term health insurance) may still use medical underwriting and can decline applicants.

Eligibility for group coverage is also tied to membership in the group — usually full-time employment status (commonly 30+ hours per week). A waiting period of up to 90 days may apply before new hires become eligible. In individual coverage, anyone who meets basic residency requirements can apply, and enrollment is restricted to the annual Open Enrollment Period or Special Enrollment Periods triggered by qualifying life events such as marriage, birth of a child, or loss of other coverage.

Portability and Continuation

Individual policies are highly portable — the policy belongs to the individual and remains in force as long as premiums are paid, completely independent of employment status. Changing jobs does not affect an individual health policy.

Group coverage is tied to membership in the sponsoring group. When an employee leaves the employer — through resignation, termination, retirement, or a reduction in hours — group coverage ends. Federal law (COBRA) allows most former employees of companies with 20 or more employees to temporarily continue their group coverage for up to 18 months (longer in some cases), but they must pay the full premium themselves, plus a 2% administrative fee. State "mini-COBRA" laws provide similar rights for employees of smaller businesses.

Premium Payment and Tax Treatment

In group plans, the employer typically pays a significant share of the premium (often 70–80%), and the employee's contribution is usually deducted from payroll before taxes through a Section 125 Cafeteria Plan, reducing the employee's taxable income. In individual coverage, the individual pays the entire premium with after-tax dollars (unless self-employed or covered by an Individual Coverage HRA). Lower-income individuals may qualify for premium tax credits on ACA Marketplace plans to reduce net costs.

Feature	Group Health Insurance	Individual Health Insurance
Contract holder	Employer (master policy)	Individual policyholder
Member receives	Certificate of coverage	Full insurance policy
Underwriting	Group-based; guaranteed issue (ACA)	Individual-based; health-status neutral (ACA)
Eligibility	Employment-based; waiting periods apply	Open to legal residents; enrollment windows
Premium sharing	Employer + employee	Individual pays 100%
Tax treatment	Employee share usually pre-tax	Post-tax (exceptions apply)
Portability	Tied to employment; COBRA available	Fully portable
Primary law	ERISA, HIPAA, ACA	State insurance law, ACA