If a married couple who each have health insurance through a job wants to switch  coverage from one employer to the other, usually it’s a snap. During the fall open enrollment period the husband, for example, can simply drop his on-the-job coverage for the new year and his wife can add him to her plan Jan. 1.

Since many companies have calendar year coverage periods, that’s the way it typically works.

But switching to a spouse’s plan can be problematic when plan coverage periods for them aren’t in sync—for example, one renews in July and the other January.

A reader recently wrote in with just such a problem. Her company’s open enrollment period is going on right now and the couple wants to switch from her husband’s high-deductible plan to her employer plan, which has better coverage. But her husband’s employer is refusing to allow him to change before next July, when his company’s new coverage year begins.

The employer may be within its rights in refusing, says J.D. Piro, a senior vice president at Aon Hewitt, who leads the benefits consultant’s health law group. When coverage periods are different, it’s up to the company to decide whether it wants to allow employees to drop the company plan so they can sign up for a plan with a different coverage period, says Piro. These “change in status” rules are determined by the employer.

This is not the same as when someone gets married or has a child, for example, or if a spouse loses coverage under another employer plan. Those events can trigger a “special enrollment period,” and companies are generally required to offer employees or their family members an opportunity to enroll at that time.

To find out whether your company allows you to switch to a spouse’s plan, get a copy of the “summary plan description” from your employer, says Piro.

“Many employers aren’t aware of the complexity of the rules or they only permit changes in certain situations,” he says. Armed with the plan description, you’ll know what your company allows and you can use it, if necessary, to inform your human resources department, says Piro.

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