One spouse did not work and pay into Medicare for the 40 quarters.
Can they apply under their spouses entitlement?
If you’re at least 62 and have worked at least 10 years in Medicare-covered employment, your spouse can get Part A and Part B at 65.
If you’ve worked at least 10 years in Medicare-covered employment but aren’t yet 62 when your spouse turns 65, they won’t be eligible for premium-free Part A until your 62nd birthday. In this case, your spouse should still apply for Part B at 65, so they can avoid paying a higher Part B premium.
However, if you’re still working and your spouse is covered under your group health plan, they could delay their Part B enrollment without paying higher premiums. Publication 11036
Related Pages in How to sign up for Medicare? A & B Section