My daughter's band, was booked to do a promotion for the public library at the local mall. The mall has asked for a Certificate of Insurance listing them as an "addtional insured" for the term of the promotion. When they were just doing volunteer gigs, I understood that they were covered under my homeowners insurance, but I guess that's not true for a paid gig. Do any of you have business liability insurance for your bands? How much? With who? What does it cost?