26 U.S.C. § 6304: Fair tax collection practices

at any unusual time or place or a time or place known or which should be known to be inconvenient to the taxpayer; if the Secretary knows the taxpayer is represented by any person authorized to practice before the Internal Revenue Service with respect to such unpaid tax and has knowledge of, or can readily ascertain, such person’s name and address, unless such person fails to respond within a reasonable period of time to a communication from the Secretary or unless such person consents to direct communication with the taxpayer; or at the taxpayer’s place of employment if the Secretary knows or has reason to know that the taxpayer’s employer prohibits the taxpayer from receiving such communication. The use or threat of use of violence or other criminal means to harm the physical person, reputation, or property of any person. The use of obscene or profane language or language the natural consequence of which is to abuse the hearer or reader. Causing a telephone to ring or engaging any person in telephone conversation repeatedly or continuously with intent to annoy, abuse, or harass any person at the called number. Except as provided under rules similar to the rules in section 804 of the Fair Debt Collection Practices Act ( 15 U.S.C. 1692b ), the placement of telephone calls without meaningful disclosure of the caller’s identity. For civil action for violations of this section, see section 7433.