Taxpayer identification number
(b) Taxpayer identification number(1) In general. Taxpayer identification number means the identifying number assigned to a person under section 6109 (relating to identifying numbers, generally a nine-digit social security number for an individual and a nine-digit employer identification number for a nonindividual, e.g., a corporation, partnership, trust, or estate). An obviously incorrect number is not considered a taxpayer identification number. See 31.6011(b)-2 and 301.6109-1 of this chapter for provisions relating to obtaining a taxpayer identification number. (2) Obviously incorrect number. Obviously incorrect number means a number that does not contain nine digits or a number that includes an alpha character as one of the nine digits.