Reason To Know

http://www.irs.gov/pub/irs-pdf/p515.pdf (Page 18) Reason To Know In general, you are considered to have reason to know that a claim of foreign status or of a reduced rate of withholding is incorrect if statements contained in the withholding certificate or other documentation, or other relevant facts of which you have knowledge, would cause a reasonably prudent person in your position to question the claims made.