A pre-existing condition is any condition that you were diagnosed with before date your new health insurance starts. This can be anything from a broken bone to diabetes to a past pregnancy.

Under the ACA, with very few exceptions, all MEC health insurance policies can not deny coverage or charge you more because of pre-existing conditions.  They also cannot limit benefits for those conditions either.

There are policies sold off the Marketplace that have exclusions based on pre-existing conditions. If you purchase one of these plans, make sure to understand what the insurance company will and will not cover.