(petitioner owned high-performance Ford Mustang which was damaged in car accident by uninsured motorist; petitioner's adjusted basis in car was $25,482 and car worth $28,500 immediately before accident and $2,250 immediately after accident (difference of $26,250); cost of repair was $18,772.79 and insurance company paid $18,522.79 to body shop; car repaired and returned to petitioner in 2007; petitioner claimed $17,287 casualty loss on 2008 return; loss disallowed initially because petitioner failed to subtract insurance reimbursement and later because loss claimed in incorrect year; 20 percent accuracy-related penalty applied).