1. Whether the Court erred in not dismissing the
case for lack of jurisdiction on the ground that
no notice of deficiency was issued to petitioner
within 90 days of the date of the tax court
petition, and no notice of determination was
issued to petitioner within 30 days of the date
of the tax court petition that would permit
petitioner to invoke the Tax Court 's
jurisdiction, as mandated by 26 U.S.C. §
6213(a), invalidating the notice of deficiency
for tax years 2015 and 2016 and affecting the
Court 's jurisdiction.

2. Whether the court failed to apply the Cohen
rule appropriately concerning the estimation
of business expenses when exact
substantiation is unavailable, thereby
potentially misinterpreting the statutory mandate
for Tax Court decision reviews as outlined in 26
U.S.C. § 7482(a) and deviating from established legal
precedent that recognizes the practical limitations on
petitioner 's record-keeping.

Did the Tax Court lack jurisdiction due to improper notice of deficiency and fail to appropriately apply the Cohen rule for estimating business expenses?