Investopedia
Investopedia features Loren Locke's analysis of au pair wage requirements and regulations.
From the Article
"This figure is derived from the federal minimum wage of $7.25 per hour, [but] the calculation includes a [40%] credit for room and board."
"Asking an au pair to perform heavy housework, manage household errands not related to the children, or work beyond the allowed hours are all violations."