There is a Federal law abbreviated as HIPAA, valid in all 50 states, which says (among other things) that if you have group insurance coverage through your employer, and you change employers (and thus your group insurance coverage), the new group insurance carrier CANNOT consider any condition to be pre-existing as long as you have had continuous coverage. Continuous coverage means that there cannot be a gap longer than 62 days between the end of the old coverage and the beginning of the new coverage (excluding waiting periods), and puts a limit on lookback periods to twelve months.
Stay with me for this; it's a bit complicated.
If you had your old coverage for twelve months or longer, that's it. Assuming that you pick up the new coverage within the 62 day window (COBRA counts), they cannot consider any condition pre-existing for any time at all.
If you had your old coverage for less than twelve months, they can (CAN does not mean they WILL - not all insurance carriers use pre-existing clauses even when legally permitted) consider a condition pre-existing for no more than the difference between twelve months and the length of time you had your old coverage. Example; you had the old coverage for eight months; they can consider a condition pre-existing for no longer than four months. After that they have to cover it just like every other condition.
Another issue is that the condition itself has to have been treated within the lookback period before it can be considered pre-ex. For example, if your surgery was two years ago and you don't take any medication for it, and haven't had any periodic follow up visits within the lookback period, then it can't be considered pre-ex no matter how short your continuous coverage may have been.
By the way, the continuous coverage does not all have to have been with one employer. If you had six months of coverage with one employer, changed jobs, had eight months coverage with another employer, and now are looking at changing jobs again, you've had fourteen months continous coverage and as long as you pick up the new plan within the 62 day window, you have no pre-ex worries.
HIPAA was put into effect for the specific purpose of protecting employees who wanted to change jobs but felt compelled to stay because of the insurance and the possibility of major bills due to pre-ex conditions.
You will probably be asked to provide proof of prior coverage either when you enroll in the new plan, or when you submit your first claim under the new plan. When you are termed from the old plan, you will be sent from either the old employer or the old insurance carrier, a certificate of coverage showing the exact beginning and ending dates of your coverage. If you have not received this certificate within 45 days of the termination of the old coverage, call the insurer and ask for it. (Or the employer - the insurer and the employer have equal responsibility for sending it out, but usually it's the insurer who does so.) If by any chance you are asked for it before you receive it, tell the new carrier that you have not yet received your "HIPAA certificate" and that you will send a copy when it comes in. Insurers are used to the fact that there is a lag time to receive these. At worst, payment of a claim may be delayed until it is received, and there probably won't be even that much of a repercussion.
All of this assumes that both the old plan and the new are employer-sponsored group health plans (HIPAA does not apply to individual plans) and that you pick up the new plan no more than 62 days after the termination of the old plan.
