The 'BB+' corporate credit rating on Tucson Electric Power Co. (TEP) reflects the consolidated creditworthiness of UniSource Energy Corp. (UniSource), which is not rated by Standard&Poor's Ratings Services and incorporates UniSource's other holdings, and principally include UNS Electric and UNS Gas, two utility companies that serve portions of northern and southeastern Arizona (these companies are owned by UniSource through an intermediate holding company, UniSource Energy Services Inc.). TEP is a vertically integrated, investor-owned utility in Arizona, serving 402,000 customers within Tucson and southeastern Arizona. The company is a wholly owned subsidiary of UniSource. TEP's credit ratings are based on the consolidated creditworthiness of UniSource and its subsidiaries, of which TEP is by far the largest, generating about 96%
