Question
What is the name of your state?California.
My wife and I have medical, dental, and vision coverage through my current employer. If I change companies, and provided my new company offers the same coverage that I get now, is there any way they can refuse to cover either of us if we have preexisting health problems? One of us has a condition that requires expensive medication, and may at some point require an operation.
Answer
If you have been covered under a group health insurance plan for 12 months or more without a break, then no, there is no possible way a future employer can consider any condition pre-existing.
This holds true regardless of whether the entire 12 months is with one employer or several. 12 months of continuous coverage under (a) group health insurance plan(s) = no pre-existing clause for a new plan.
A break in coverage is defined as 63 days or more.
If you have had a break in coverage during the last 12 months, then a pre-ex clause can be enforced for the difference between the length of time you were covered, and 12 months. Example; you had a break in coverage but since then you have been covered under your current employer's plan for eight months; a new employer's plan can impose a pre-ex clause for four months.
Edited to add:
The new employer's carrier can and will require you to provide proof of such previous coverage. Either your current employer or his insurance carrier is required by law to provide you with a certificate showing this coverage within 45 days of the coverage's termination.