If you have health insurance through your employer at age 65, you may be able to delay Medicare enrollment without penalty. But the rules depend critically on your employer's size, and one of the biggest mistakes New Mexicans make is assuming COBRA counts as employer coverage—it does not.
The 20-Employee Rule
When you have both Medicare and other coverage, one is the "primary payer" (pays first) and the other is the "secondary payer" (pays after). The size of your employer, and whether you are still working, decides which is which:
| Your Coverage | Primary Payer | Secondary Payer | Should You Take Part B? |
|---|---|---|---|
| Current job, 20 or more employees | Employer plan | Medicare (if enrolled) | Usually delay Part B to avoid premiums |
| Current job, fewer than 20 employees | Medicare | Employer plan | Yes—enroll in Part B at 65 |
| Retiree plan (not an active employee) | Medicare | Retiree plan | Yes—a retiree plan does not let you delay Part B |
| COBRA (after the job ends) | Medicare | COBRA | Yes—within 8 months of the job ending |
Critical: If you work for a company with fewer than 20 employees and delay Part B, your employer plan can refuse to pay claims that Medicare would have covered. You could face large bills, because the employer plan may pay only its secondary share.
Large Employer (20+): What to Expect
If your employer, or your spouse's employer, has 20 or more employees and you are covered through that current job:
- The employer plan stays primary as long as you (or your spouse) are still actively working
- You can delay Part B without a penalty, because the coverage is based on current employment
- Consider premium-free Part A, unless you or your employer contribute to an HSA (any Medicare enrollment ends HSA contributions)
- When the job or the coverage ends, whichever comes first, you have an 8-month Special Enrollment Period to sign up for Part B
Small Employer (Fewer Than 20): Medicare Is Primary
This is where many people get caught. If your employer has fewer than 20 employees:
- Medicare is your primary payer starting at age 65, even if you haven't enrolled
- Your employer plan may pay only what Medicare wouldn't—so if you're not enrolled in Medicare, you can be left with large bills
- Enroll in Parts A and B at 65 to avoid this problem
- Your employer plan becomes secondary, paying after Medicare
Many New Mexico small businesses, professional practices, ranches, and family-owned companies fall into this category. If you work for a small employer in New Mexico and are approaching 65, this is the most important rule to understand. Ask your employer's benefits contact how the plan pays once you're eligible for Medicare.
The COBRA Myth
Many New Mexicans believe COBRA counts as "current employer coverage" for Medicare purposes. It does not. COBRA is not considered active employer coverage by Medicare, which means:
- COBRA does not entitle you to a Special Enrollment Period for Part B
- If you leave a job and take COBRA, your 8-month Part B Special Enrollment Period still starts when the job or the employer coverage ends, whichever comes first—not when COBRA ends
- If you have COBRA at 65 and don't enroll in Part B, you'll face permanent late penalties: 10% more for each full 12-month period you could have had Part B but didn't
- Medicare pays first; COBRA pays second (if at all)
- If you are turning 65 while on COBRA, enroll in Part B during your Initial Enrollment Period, not when COBRA ends
The COBRA trap: Some retirees take 18 months of COBRA, assuming they can enroll in Medicare when COBRA ends. By then, 18 months have passed since the job ended, so the 8-month Special Enrollment Period is long gone. The result: they can sign up only during the General Enrollment Period (January 1 to March 31, with coverage starting the month after they sign up) and pay a permanent Part B late penalty.
Federal Employees: Different Rules
For New Mexico's federal workforce (Kirtland AFB, White Sands, DOE/NNSA and other federal agencies), FEHB follows the same current-employment rule, with a few details to know. LANL and Sandia employees work for the labs' contractors and generally have the contractors' plans, not FEHB.
- While you (or your spouse) are still a federal employee, FEHB is current-employment coverage, so you can delay Part B and use the 8-month SEP when that job ends
- After retirement, FEHB does not protect you: if you skip Part B when you retire, you can sign up later only from January 1 to March 31, and you will pay a permanent late penalty
- FEHB is creditable drug coverage, so it does protect you from the Part D late penalty, even as a retiree
- Adding Part A is recommended (it's premium-free for most), unless you are contributing to an HSA
- Adding Part B at retirement can lower out-of-pocket costs
See our full FEHB & Medicare guide →
Self-Employed and Marketplace Coverage
If you're self-employed or have ACA Marketplace coverage at 65, neither counts as "current employer coverage" for Medicare. You should enroll in Medicare Parts A and B during your Initial Enrollment Period to avoid late penalties.
If You're Covered Through Your Spouse's Job
If you turn 65 first but your spouse still works at an employer with 20 or more employees:
- You can stay on your spouse's employer plan as a dependent
- Their plan is primary; Medicare (if enrolled) is secondary
- Consider premium-free Part A, unless an HSA is involved
- You can delay Part B without a penalty
- When your spouse stops working or you lose the coverage, whichever comes first, you have 8 months to sign up for Part B
See our detailed spouse coverage guide.
What Lets You Delay Part B or Part D?
Part B and Part D use different tests. You can delay Part B without a penalty only with group health coverage based on your or your spouse's current job. You can delay Part D with any drug coverage that is "creditable" (at least as good as standard Part D).
| Coverage Type | Lets You Delay Part B? | Creditable for Part D? |
|---|---|---|
| Group plan from your or your spouse's current job | YES (if fewer than 20 employees, Medicare still pays first) | Usually YES (check the annual notice) |
| FEHB while you or your spouse still work for the government | YES | YES |
| FEHB as a retiree | NO | YES |
| TRICARE while the sponsor is on active duty | YES | YES |
| TRICARE For Life (military retirees) | NO—you need Part A and Part B to keep it | YES |
| VA health benefits | NO | YES |
| Indian Health Service | NO | YES |
| COBRA | NO | Sometimes (check the notice) |
| Retiree health plan | NO | Sometimes (check the notice) |
| Marketplace plan | NO | Ask the plan |
More on drug coverage: Part D & creditable coverage.
Coordination of Benefits: How It Works
When you have both Medicare and an employer plan, claims are processed in a specific order:
- Your provider sends the bill to the primary payer first
- The primary payer covers their portion based on the plan's rules
- The secondary payer covers some or all of the remaining balance
- You pay any leftover amount
Generally, having both Medicare and a strong employer plan can lower your out-of-pocket costs.
Free Help With Coordination Questions
Government help
- Medicare: 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, or Medicare.gov
- Social Security (Part B enrollment and Form CMS-L564): 1-800-772-1213 or ssa.gov
Licensed insurance agents (Benefits Life)
- Benefits Life licensed insurance agents: 505-MEDICARE (505-633-4227), TTY 711
Don't Guess—Get Help From a Licensed Agent
Coordination-of-benefits decisions for working New Mexicans depend on many details of your situation. A licensed insurance agent can review your specific employer plan, check its creditable coverage notice, and help you choose the right Medicare timing.