Florida and New York seniors often are charged much more for their Medicare supplemental insurance, according to a recent study by Weiss Ratings Inc., a provider of independent financial ratings on insurance companies. The study analyzed 38,000 Medigap quotes from 113 insurers across the nation.

Congress created the 10 Medigap plans A through J in 1992 to augment Medicare coverage. Although each state has identical coverage for a lettered plan, this standardization of coverage has not translated into the standardization of price, the study reveals. (See The 10 standardized Medigap plans.) Premium costs vary widely not only from state to state, but also from cities within the same state and from insurer to insurer.

For example, a 65-year-old female in Salt Lake City would pay $504 for Plan A with Regence Blue Cross Blue Shield of Utah, according to the study. Yet, the same individual would pay $1,360 — almost three times more — for the exact same plan in Miami with Bankers Life & Casualty. Even within the same city, the costs of the same plan may be double. In Lafayette, La., that 65-year-old female would be charged $2,048 for Plan F by United American Insurance Co., while Golden Rule Insurance Co. would charge her $1,096 for identical coverage.

According to Dr. Martin Weiss, chairman of Weiss Ratings, insurance companies say premium discrepancies result from the varying costs of medical care from region to region, and the fact that some companies make a commitment to long-term price stability while others do not.

"The more pertinent factor," he adds, "is that some companies are aggressively bidding for new business, while others are simply charging inflated prices." Weiss urges consumers to shop around and consider each insurer's financial strength in addition to premium prices.