Specific instructions are required before OPM may pay any arrearage. Except as provided in § 838.225(b) , OPM will not increase a former spouse's share of employee annuity to satisfy an arrearage due the former spouse. However, under § 838.225 , OPM will prospectively honor the terms of an amended court order that either increases or decreases the court order's entitlement.
5 C.F.R. §838.234