If you’re about to turn 65, you may be shopping soon for a health plan that covers the costs that traditional Medicare doesn’t.

As welcome as Medicare’s health care coverage is, it does have its gaps. The traditional fee-for-service program generally pays 80 percent of the medical bills. Which means the remaining 20 percent becomes the responsibility of beneficiaries.

o protect themselves, many people buy supplemental coverage from private insurers. The “Medigap” insurance, as it’s called, helps fill the gaps that deductibles, copayments and coinsurance leave. It makes out-of-pocket costs more manageable.

About one in four Medicare beneficiaries does purchase a Medigap policy.