Yes, if more than $500,000 is in dispute ($100,000 in rural areas), you filed a timely first appeal, and FEMA denied it or didn’t decide within 180 days. You choose arbitration or a second appeal, not both, and the Civilian Board of Contract Appeals (CBCA) decision is final.
The first appeal and its decision (or proof of 180 days with no decision), the amount in dispute, and the arbitration request sent to all three parties.
Weigh arbitration early. It is final, there’s no further appeal, and your representation costs are your own, so it works best for large, well-documented disputes.