Unless you are age 65+ and have personally experienced Medigap in all its complexity, it's difficult to know where to start evaluating coverage options.

Read: Retirement savers must plan for health care sticker shock

Now, there is help–and you can find it for free at the Medicare.gov site. There you can download a PDF file of the 2015 edition of Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare, a publication developed jointly by the Centers for Medicare & Medicaid Services (CMS) and the National Association of Insurance Commissioners (NAIC).

The guide is a model for consumer educational information that is both comprehensive in scope and easy to understand.

Written in plain English, it takes clients from the basics of Medicare coverage to the array of standardized Medigap plans available.

It includes a checklist of information a consumer should know to buy a Medigap policy, along with guidance on the best time to evaluate coverage.

The guide includes resources for shopping the Medigap market, state-by-state, and a useful glossary of terms you should know, with clear definitions you can use in client conversations.

All the guide lacks is information for comparing current costs of Medigap plans in a specific market. This is very important because, as it states: "There can be big differences in the premiums that different insurance companies charge for exactly the same coverage."

Until recently, Weiss Ratings offered a subscription data base that described costs and benefit of most plans available in each zip code. However, Weiss says it has discontinued the service.

The best alternative may be to contact your State Health Insurance Assistance Program at the phone number listed in the guide.

For healthier seniors, it's also a good idea to compare the cost of Medicare Part C (Medicare Advantage) with stand-alone Medigap plans. Part C bundles all benefits and services covered under Parts A and B and usually includes Part D (prescription drug coverage) as part of the plan.

Part C usually is less expensive than paying separate premiums for Parts B, D and Medigap. However, benefits also may be less generous.

Solving the Medigap maze is among the most difficult challenges people face in their mid-60s. (In comparison, enrolling in Medicare Parts A and B usually is a piece of cake.)

If you can simplify the analysis and help to save premium dollars, your senior clients won't forget the assistance.

They also will keep coming back year-after-year to review Medigap coverage options.