Revoking Waiver of COBRA Coverage
If you decided to waive COBRA coverage during the initial election period and then change your mind, you can do so as long as you revoke the waiver of coverage before the end of the election period. If the election period has passed then unfortunately you cannot revoke your waiver. After you revoke the waiver, simply elect COBRA coverage but the plan only needs to provide continuation coverage beginning the date of the waiver.
For example, if you elected to revoke your waiver of COBRA coverage on January 15th because you suffered an event on the 14th, your COBRA plan may not cover you for that event on the 14th because they are only obligated to cover you after the date of your waiver.