We had that happen where I worked; first, go to whatever department sent you the letter and make sure it's right for you; could be they've changed plans and you're on "family" plan accidentally or something. Not all plans translate to one another well, year to year. Every year companies have to renegotiate their health insurance plans based on the ages of their employees and how many claims were made, etc.

So, (1) make sure there wasn't a mistake, (2) make sure you understand it well -- usually you have to sign that you understand and select a plan, etc. Make sure they haven't changed from "monthly" to "quarterly" or something simple (but confusing) like that or changed plans completely and think you want to insure your 12 children too :-) If you do have a family plan; we had one couple that worked for our company and they each had to insure one of their children as "parent + one child" each was less expensive than the "family" plan for all of them. The biggest problem we had though with why something jumped so high was because people were in the "high priced" plan where you can go to any doctor at any time or place and everything's covered, etc. rather than the "company" plan where you select a doctor from a book, etc. Some people accidentally got mixed up and it really was a huge jump just because the names of the plans for the two different companies doing the insuring were similar but what they offered was different.