Speak Out to Stop Child Abuse Act or SOS Child Abuse Act - Amends the Child Abuse Prevention and Treatment Act to require the state plan under a grant from the Secretary of Health and Human Services (HHS) for child abuse and neglect prevention and treatment programs to contain an assurance in the form of a certification by the state governor that the state has in effect and is enforcing a state law prescribing a criminal penalty against an individual age 18 or older who fails to report to a state or local law enforcement official or child protective services that the individual has witnessed another individual in the state engaging in sexual abuse of a child.