Example. The IRS hand delivers a written request for the list required to be maintained under section 6112 to Firm B, a material advisor, on Friday, March 10, 2017. Firm B must make the list available to the IRS on or before Friday, April 7, 2017, the 20th business day after the request was hand delivered. If Firm B fails to make the list available to the IRS by that day, absent reasonable cause or the IRS's grant of an extension of the response time, the $10,000-per-day penalty begins on Saturday, April 8, 2017. The $10,000 per day penalty will continue for each subsequent calendar day until Firm B makes the complete list available, except for those days for which Firm B demonstrates reasonable cause. If Firm B hand delivers a complete copy of the requested list to the IRS on the morning of Tuesday, April 11, 2017, absent reasonable cause or the IRS's prior grant of an extension for the response time, a penalty of $30,000 will be imposed upon Firm B (for April 8, 9, and 10). See paragraphs (g) and (h) of this section for an explanation of reasonable cause.
26 C.F.R. §301.6708-1