In most cases, your health insurance coverage will not take effect immediately. There are general effective date rules that apply each year during open enrollment and during special enrollment periods triggered by qualifying events, which are addressed below.
Open enrollment begins November 1 and continues through at least January 15 in nearly every state (only Idaho utilizes a December deadline).
In most states, enrollments completed by December 15 will have a January 1 effective date, and enrollments completed between December 16 and January 15 will have a February 1 effective date.
But several state-run exchanges allow enrollments to be completed as late as December 31 and still have a January 1 effective date. And some state-run exchanges have open enrollment deadlines as late as January 31, generally with a February 1 effective date for people who enroll in January.
In addition, if any insurers exit the market or terminate certain plans (replacing PPOs with HMOs, for example) at the end of the year, the people enrolled in those plans will be eligible for special enrollment periods. The special enrollment period, in that case, will run for 60 days before and 60 days after the loss of coverage.
People in this situation who pick a replacement plan before the end of December will have coverage effective January 1 (even if they enrolled after December 15). If they pick a replacement plan in the first 60 days of the new year, their new plan will take effect the month after the enrollment is completed.
Outside of open enrollment (meaning you’re enrolling due to a qualifying life event), coverage will typically take effect the month after the enrollment is completed, regardless of the date of the enrollment (so an enrollment completed on August 1 or August 31 would have a September 1 effective date).
There are still some state-run exchanges that utilize a first-of-the-second-following-month for special enrollment SEP period enrollments completed after the 15th of the month. But starting in 2025, all states will have to allow coverage to start the first of the month after the enrollment is completed during a SEP, regardless of the date it’s submitted. The federally-run Marketplace (HealthCare.gov) switched to that approach as of 2022, and all states will be using that approach by 2025, under the terms of a rule change that was finalized in 2024. 1
If the special enrollment period is due to the birth or adoption of a child, the coverage can be retroactive to the birth or adoption date, as opposed to taking effect at the start of the month following the enrollment. 2
When the SEP is due to involuntary loss of other coverage, the new plan will generally take effect the first of the month following the loss of other coverage, as long as the application is submitted during the month the old coverage ends. But due to a rule change that was finalized in 2023, a mid-month loss of other coverage can allow a person to get new coverage effective the first of the month during which their old coverage will end, instead of the first of the following month. This will result in double coverage for the first part of the month, but avoids a coverage gap later in the month. This is optional for state-run exchanges, but it’s offered via the federally-run exchange. 3
To take advantage of this option, you must submit your SEP enrollment before the first day of the month in which your coverage will end. So for example, if your plan is going to end on October 15, you would need to submit a SEP enrollment by September 30 to have an October 1 start date (and thus have double coverage for the first half of October, but no gap in coverage for the second half of October). If you wait and submit your application on October 1, your new coverage won’t take effect until November 1.
If your old plan ends mid-month, and COBRA is an option, you could have your new plan take effect the first of the following month (ie, resulting in a partial month gap in coverage) and retroactively elect COBRA if a medical need were to arise before the new plan takes effect.
If you wait and enroll during the 60 days after your old plan ends, you will have a gap in coverage as your new coverage will take effect the first of the month following your enrollment. But again, the option to retroactively elect COBRA might give you another alternative if you were to need medical care during that time.
Outside the exchanges, effective dates generally follow the same rules as inside the exchanges. However, some insurers in some states opt to extend the enrollment deadline to December 31 for coverage effective January 1, if the person is applying outside the exchange during open enrollment. This is carrier-specific, so you would need to check with the insurance company to see what their deadlines are.
States also have the option to impose stricter limits on open enrollment for off-exchange plans. New Mexico is an example of this, with an off-exchange open enrollment period that ends on December 15, a month before the open enrollment period ends for on-exchange plans. 4
If you’re enrolling in a non-ACA-compliant plan (like a short-term health plan), coverage can be effective as soon as the day after you enroll, but the insurer can use medical underwriting to determine your eligibility for coverage.
Louise Norris is an individual health insurance broker who has been writing about health insurance and health reform since 2006. She has written dozens of opinions and educational pieces about the Affordable Care Act for healthinsurance.org.
