COBRA lets you keep your employer's group health plan after leaving a job, but you pay the full premium yourself plus a small administrative fee. You generally have 60 days from the coverage-loss date or the notice date to elect, whichever is later, and coverage can last 18 months for a voluntary quit. The catch most thin explainers miss: you owe retroactive premiums back to the loss date if you elect late.
Most people learn about COBRA in the worst possible moment — the exit interview, holding a benefits folder they will not open for three weeks. That delay is expensive, because the clock on COBRA starts whether or not you are paying attention. This explainer walks through the actual regulatory machinery, the numbers that matter, and the failure modes that cost people thousands.
The qualifying-event trigger mechanism
COBRA does not switch on when you stop showing up for work. It switches on when a qualifying event causes a loss of coverage under the group plan. For a voluntary resignation, the qualifying event is the termination of employment, and the loss of coverage usually falls at the end of the month in which you leave. For an involuntary termination that is not gross misconduct, the same trigger applies but the maximum duration extends to 29 months if the person is determined disabled under Social Security rules.
Three entities have to act in sequence for the machinery to run. The employer must notify the plan administrator within 30 days of the qualifying event. The plan administrator must then send the COBRA election notice within 14 days after that. The qualified beneficiary — you and any covered spouse or dependent children — then has an election window measured from the later of the coverage-loss date or the notice date. That sequencing explains a common confusion: the 60-day election clock is often longer than 60 days from your last day, because the notice itself takes weeks to arrive.
The mechanism exists because group health plans are priced on pooled risk. When you leave, you exit the pool, and the plan has no contractual obligation to keep covering you. COBRA is a statutory bridge that forces the plan to keep offering the same coverage at a price the employer can charge without subsidy. The employer is not required to contribute; it is only required to offer.
Quantified context: what it actually costs
The premium is the core number. Under COBRA you pay the full group premium, both the employee share and the employer share, plus an administrative fee capped at 2 percent of the premium. If your employer was paying USD 500 per month toward a family plan and you were paying USD 200, your COBRA premium is roughly USD 714 (USD 700 plus 2 percent). For a single plan with a USD 450 total premium, you would pay about USD 459.
Compare that with an individual marketplace plan. A benchmark silver plan for a 40-year-old often sits in the USD 400–600 range before subsidies, and subsidies can bring that down sharply depending on income. That comparison drives most of the decision: COBRA preserves your network, your deductible progress, and your existing providers, but often at a higher sticker price than a subsidized marketplace plan.
Election window and retroactivity timeline
| Phase | Timing | What happens |
|---|---|---|
| Coverage loss | End of month of termination | Active coverage ends |
| Employer notice to plan | Within 30 days | Clock starts on administrator |
| Election notice sent | Within 14 days of employer notice | You receive packet |
| Election window | 60 days from later of loss date or notice date | You may elect |
| Premium due | 45 days after election | First payment deadline |
| Retroactive coverage | Back to loss date | Claims reprocessed |
| Maximum duration | 18 months (29 if disabled) | Coverage endpoint |
The retroactivity is the mechanism that trips people up. If you elect on day 55 and pay on day 90, your coverage is treated as continuous back to the loss date. Any claims incurred in that gap get reprocessed and paid as if you never lapsed. But if you never elect, those claims are simply denied, and you cannot go back and elect after the window closes. This is why the 60-day window is best treated as a decision deadline, not a grace period.
Edge cases that change the math
Small employers are exempt. COBRA applies to private employers with 20 or more employees in the prior year, counted using a specific full-time-equivalent method. If your employer had 19 employees, federal COBRA does not apply, though many states have mini-COBRA laws that fill the gap with shorter durations, often 6 to 18 months. The threshold is 20, not 50 — that is the ACA employer mandate number, and conflating the two is a common error.
Medicare interacts in a way that surprises people. If you become entitled to Medicare before or during COBRA, the Medicare entitlement generally ends COBRA for the spouse and dependents but not for the person on Medicare. The Medicare Secondary Payer rules also mean group coverage typically pays secondary once Medicare is primary, which can change what COBRA is worth.
Moving out of the plan's service area does not automatically end COBRA, but it may leave you with no in-network providers. Some plans offer a conversion option or a different network tier. The rule is that COBRA preserves the plan as written, not a plan that fits your new ZIP code.
A counterintuitive detail worth flagging: electing COBRA and then dropping it later does not let you re-elect. COBRA is a one-shot election per qualifying event. If you elect, pay for three months, then cancel, you cannot restart the same coverage for the same event. The professional caveat: some plans permit a second election only in narrow circumstances, and you should confirm in writing before relying on it.
Potential red flags to watch for in your packet:
A notice that lists a premium higher than the total plan premium plus 2 percent A coverage-loss date that does not match your last day of active coverage Missing information about dependents or a spouse No mention of the 60-day election window or the 45-day payment deadline A demand for payment before the election window has run
Misconceptions worth correcting
The biggest misconception is that COBRA is free or subsidized. It is neither. The only subsidy that ever applied broadly was the 2009–2010 premium reduction under the American Recovery and Reinvestment Act, which expired. Do not build a budget around a subsidy that no longer exists.
The second is that COBRA is always the best bridge. For healthy people with modest claims, a marketplace plan with subsidies can cost less per month and still cover preventive care at no cost. For people mid-treatment, mid-deductible, or with a narrow provider network, COBRA often wins on continuity even at a higher premium. The decision is not about which is cheaper in the abstract; it is about which preserves the care you are actually using.
The third is that COBRA covers everything the group plan covered. It does, but only to the same extent and under the same terms. If the employer changes the plan mid-year, your COBRA coverage changes with it. You are riding the plan, not locking a snapshot of it.
A fourth misconception: people assume the 18-month clock starts on their last day. It generally starts on the coverage-loss date, which is often the end of the month. That difference of up to 30 days matters at the tail end, especially if you are timing a transition to Medicare or a new employer's plan.
Practical actions with thresholds
Treat the first 10 days after your last day as the working window. Confirm your coverage-loss date in writing with HR. Ask for the total plan premium for your tier, not just your payroll deduction. That single number tells you whether COBRA is viable.
At the 30-day mark, if you have not received the election notice, contact the plan administrator in writing. The 14-day administrator deadline is a legal requirement, and a paper trail protects you if the notice was lost. Keep the envelope and any dated correspondence.
At day 45 to 55 of the election window, make the call. If you are still undecided, elect COBRA to preserve the retroactive option, then cancel later if a marketplace plan is approved and active. Electing costs nothing until the premium is due, and the 45-day payment window gives you room. This is the single highest-value tactic in the entire process: elect early, decide late.
Use these thresholds as decision gates:
If total COBRA premium exceeds 1.5 times the subsidized marketplace premium for comparable coverage, price the marketplace seriously. If you are mid-deductible with more than USD 1,000 in expected claims, COBRA's continuity usually wins. If your providers are out-of-network on every marketplace plan in your area, COBRA is often the only way to keep them. If you are within 6 months of Medicare eligibility, check the Medicare interaction before electing.
Document everything. Save the election notice, the premium quote, the payment confirmations, and any denial letters. If a claim is wrongly denied during a retroactive period, the paper trail is what gets it reprocessed.
Limitations and what COBRA cannot do
COBRA does not create coverage. It extends an existing plan for a defined period. It does not guarantee the plan will stay the same, does not cap the premium, and does not cover you if the employer terminates the plan entirely — though plan termination for all participants ends COBRA for everyone. It also does not apply to most small employers, church plans, or certain governmental plans, which have their own rules.
The 18-month maximum is a floor, not a ceiling, in some cases: disability extends it to 29 months, and certain events like a second qualifying event (divorce, death, a dependent aging out) can extend it to 36 months for affected dependents. Those extensions are fact-specific and require notice. The rule to remember is that COBRA duration is measured from the original qualifying event, not reset by later events.
Finally, COBRA is a bridge, not a destination. It buys time to find a permanent plan — a new employer's coverage, a marketplace plan, or Medicare. The people who get hurt are the ones who treat the 18 months as a finish line rather than a runway.
This article is general educational information about how COBRA works, not a legal opinion, tax advice, or a recommendation about any specific plan. COBRA rules interact with state mini-COBRA laws, Medicare, and individual plan terms in ways that require a qualified benefits attorney or licensed insurance professional to evaluate for your situation. If you are facing a coverage gap and cannot afford care, contact your state insurance department or a local navigator for direct assistance.