How long does COBRA last? That depends on the Qualifying Event.

October 9, 2025

When clients ask, “How long does COBRA last?” the answer is: it depends.
The maximum continuation period varies based on why coverage was lost (the “qualifying event”) and who is affected (employee vs. spouse or dependents).

Here’s a plain-English guide you can share.

COBRA Continuation Maximum Periods by Qualifying Event
Qualifying Event Who’s Affected Maximum Period
Termination of employment (other than gross misconduct) or reduction in hours Employee and covered dependents 18 months
Death of the employee Spouse/dependents 36 months
Divorce or legal separation Spouse/dependents 36 months
Dependent child loses eligibility (ages out, no longer a student if required, etc.) That dependent child 36 months
Employee becomes entitled to Medicare (special timing rules) Usually spouse/dependents in specific scenarios Up to 36 months (measured from Medicare entitlement if it preceded an 18-month event)
Disability extension after an 18-month event (SSA disability determination) Employee and covered dependents 29 months total (18 + 11)

Note: COBRA generally applies to employers with 20+ employees; smaller employers may be subject to state continuation rules. For the Medicare row, the special 36-month timing applies to spouse/dependents when Medicare entitlement occurred before the 18-month event.

Note: COBRA generally applies to employers with 20+ employees. Smaller employers may be subject to state continuation instead.

The 18-Month Events (Employee Triggers)

Two events typically start an 18-month COBRA clock—for the employee and any dependents covered at that time:

  • Termination of employment (for reasons other than gross misconduct)

  • Reduction in hours (e.g., moving from full-time to part-time)

If nothing else occurs, the maximum for everyone affected is 18 months.

Example:
Alex drops from 40 to 20 hours per week and loses coverage. Alex, Alex’s spouse, and dependent child can each elect COBRA for up to 18 months.

The 36-Month Events (Dependent Triggers)

Certain dependent-only events trigger up to 36 months of COBRA coverage:

  • Death of the employee

  • Divorce or legal separation

  • Dependent child losing eligibility (aging out or no longer a student)

If these events occur while the family is covered under the plan—or even during COBRA—the spouse and/or dependents can continue coverage for up to 36 months from that event.

Where Medicare Fits In

You’ll often see “employee becomes entitled to Medicare” listed as a qualifying event.
But this one’s tricky.

For active employees in groups of 20+, the Medicare Secondary Payer (MSP) rules make the employer plan primary. Employers generally can’t remove employees just because they turn 65 or enroll in Medicare—so no COBRA event occurs.

Medicare matters only when it actually causes a loss of coverage, such as:

  • Retiree medical coverage that ends when the retiree (or spouse) becomes Medicare-eligible

  • Very small groups not subject to COBRA (where state continuation may apply)

Special timing rule:
If the employee became entitled to Medicare before an 18-month event (termination or reduction in hours), the spouse/dependents can receive up to 36 months from the Medicare entitlement date.
The employee still gets 18 months from the termination/hours reduction.

Example:
Maria enrolls in Medicare Part A on March 1. Four months later, she’s laid off and loses coverage.

  • Maria gets 18 months from her layoff.

  • Maria’s spouse can receive up to 36 months from March 1 (the earlier Medicare entitlement).

Second Qualifying Events (Extending to 36 Months)

If an 18-month COBRA event (termination or hours reduction) is followed by another qualifying event during that period—like death, divorce, Medicare entitlement, or a dependent aging out—the spouse/dependents may extend their coverage to 36 months total from the first event’s date.

They must notify the plan within the required timeframe.

Example:
Chris is terminated and COBRA begins January 1. Ten months later, Chris and spouse divorce.
The spouse’s COBRA extends so that the total coverage from January 1 equals 36 months.

Disability Extension (18 → 29 Months)

An 18-month COBRA period can extend to 29 months if any qualified beneficiary is determined disabled by the Social Security Administration during the first 60 days of COBRA coverage.

  • The extension applies to all family members on COBRA.

  • The plan may charge up to 150% of the regular premium for months 19–29.

  • The family must notify the plan within 60 days of the SSA determination and before the original 18 months expires.

Practical Tips for Agents and Employers

  • Mark the calendar early. COBRA clocks run from the date of the qualifying event, not when paperwork is processed.

  • Understand the MSP rule. For large groups, Medicare doesn’t usually trigger COBRA for active employees.

  • Watch for second events. They’re the most common reason dependents move from 18 to 36 months.

  • Don’t forget state continuation. Small, fully insured groups follow state rules, which vary—and some states offer continuation after COBRA ends.

  • And one more tip: don’t handle COBRA administration on your own. Partnering with an experienced third-party administrator (TPA) is an inexpensive way to ensure accuracy and compliance while avoiding costly mistakes or penalties.

Bottom Line

“How long COBRA lasts” really means “what happened and to whom.”
Start with the event, apply the correct maximum—18, 29, or 36 months—and watch for second events or disability determinations that change the timeline.

When in doubt, loop in your COBRA administrator to confirm the clock.