1 EXHIBIT 21 Subsidiaries of ACMAT Corporation Listed are the subsidiaries of ACMAT Corporation: STATE OF NAME OWNERSHIP INCORPORATION - ------------------- --------- ------------- ACMAT Companies 100% Delaware AMINS, Inc. 100% Connecticut Geremia Electric Co. 100% Connecticut ACSTAR Holdings, Inc. 100% Delaware ACSTAR Insurance Co. (1) 100% Illinois ACMAT of Texas, Inc. 100% Delaware United Coasts Corporation 84% Delaware United Coastal Insurance Company (2) 100% Arizona (1) Owned 100% by ACSTAR Holdings, Inc. (2) Owned 100% by United Coasts Corporation 67