5 CFR §839.602

1. (a)If your qualifying retirement coverage error was not previously corrected and you fail to make an election within the time limit under § 839.611(a), your retirement coverage is summarized in the following chart:
2. (b)If your qualifying retirement coverage error was previously corrected and you fail to make an election within the time limit under § 839.611(b), you are considered to have elected to remain in your current retirement plan.