Quick Answer: OEP is the annual ACA enrollment window. For 2027 coverage, it runs November 1, 2026 through January 15, 2027 on HealthCare.gov and most state Marketplaces. Medicare uses a separate Annual Enrollment Period (AEP) , check the [Medicare eligibility](/medicare-eligibility) rules if you turn 65 in 2026. Households below 138% of the [Federal Poverty Level](/federal-poverty-level) in expansion states often go to [Medicaid](/medicaid-income-limits) instead, which has year-round enrollment.
Annual Open Enrollment Period (OEP) Limits
Current annual limits| Enrollment window | Dates | Coverage starts |
|---|
| ACA Marketplace OEP | Nov 1, 2026 to Jan 15, 2027 | Jan 1 or Feb 1, 2027 |
| Medicare Annual Enrollment (AEP) | Oct 15 to Dec 7, 2026 | Jan 1, 2027 |
| Medicare Advantage OEP | Jan 1 to Mar 31, 2027 | First of month after switch |
2026-2027 enrollment chart by program. Source: HealthCare.gov and Medicare.gov 2026.
Source: https://www.healthcare.gov/quick-guide/dates-and-deadlines/
Example: How It Works in Practice
Worked example: today is November 15, 2026. The ACA OEP opened two weeks ago and is open until January 15, 2027, so you have about 2 more months to enroll for 2027 coverage. If you miss it, your next chance is a Special Enrollment Period.
Worked example| Enroll by | Coverage begins |
|---|
| December 15, 2026 | January 1, 2027 |
| January 15, 2027 | February 1, 2027 |
Source: HealthCare.gov 2026 enrollment dates.
Frequently Asked Questions
When is Open Enrollment for 2027 ACA coverage?
ACA Marketplace OEP runs November 1, 2026 through January 15, 2027 in most states. Enroll by December 15, 2026 for coverage starting January 1, 2027. Enroll between December 16, 2026 and January 15, 2027 for coverage starting February 1, 2027. State-based Marketplaces (California, New York) sometimes extend deadlines.
What's the difference between OEP and AEP?
OEP usually refers to the ACA Marketplace window (Nov 1, 2026 through Jan 15, 2027). AEP is the Medicare Annual Enrollment Period (Oct 15 through Dec 7, 2026) for Medicare Advantage and Part D. Medicare also has a Medicare Advantage OEP (Jan 1 through Mar 31, 2027) for existing MA enrollees to switch plans once.
Can I enroll in ACA Marketplace coverage outside OEP in 2026?
Only with a [Special Enrollment Period](/glossary/special-enrollment-period) triggered by a qualifying event (job loss, marriage, baby, move, lost Medicaid). Without an SEP, you wait until the next OEP. Medicaid and CHIP have year-round enrollment regardless of OEP, so check [Medicaid eligibility](/medicaid-income-limits) first.
How do I enroll during the 2026 OEP?
Visit [HealthCare.gov](https://www.healthcare.gov) starting November 1, 2026, or your state Marketplace. Have income documents and Social Security numbers ready. The site calculates your Premium Tax Credit automatically. Free help is available through certified navigators and brokers listed on HealthCare.gov.
