5 CFR §839.1302

1. (a)You can appeal to the MSPB a decision that affects your rights and interests under this part, except an OPM decision under subpart L (see § 839.1303). Some examples of decisions are:
   1. (1)Your employer's determination that your error is not subject to these rules;
   2. (2)Your employer's determination that you are not eligible to elect retirement coverage under these rules; and
   3. (3)OPM's denial of your request for a waiver of the time limit for making an election.
2. (b)You may not seek review of a decision under any employee grievance procedures, including those established by chapter 71 of title 5, United States Code, and 5 CFR part 771.