On January 13, 2020, the Tax Court issued a Memorandum Opinion in the case of Seely v. Commissioner (T.C. Memo. 2020-6). The issue presented in Seely v. Commissioner was whether the taxpayers provided sufficient extrinsic evidence to demonstrate the timely mailing of a petition, even though the envelope in which the petition was mailed bore no postmark. If so, then the Tax Court had jurisdiction to redetermine the deficiency.  If not, then no jurisdiction would