The new Trump Administration has generated significant uncertainty about the applicability of a number of tax regulations finalized in the waning days of the Obama Administration. On the day of President Trump’s inauguration, Reince Priebus, the Chief of Staff of the White House issued a memorandum to all the heads of executive agencies to pause certain of their rule-making activities until review by the President’s new appointees or designees, with very limited exceptions for emergency situations. The Chief of Staff’s memorandum directs executive agencies to: (1) refrain from sending any new regulations to the Office of the Federal Register (“OFR”) until it has been approved by an agency head appointed by President Trump; (2) withdraw those regulations that had been sent to the OFR but remain unpublished (there is typically a lag of at least one day between a regulation being sent to the OFR and its publication in the Federal Register); and (3) postpone for 60 days the effective date of any regulation that had been published in the Federal Register but had not yet taken effect.