Criminal tax cases, like any criminal case, must be tried by a jury unless both sides agree to let the judge do it alone. In civil tax cases, the taxpayer has a choice: you can pay what the IRS says you owe, and sue for a refund, in which case you get a jury trial, or you can contest the IRS's claims in Tax Court without paying first, but then you don't get a jury.
Just keep this in mind if you ever appeal to tax court: it is a court of record, not a court of law. If you try to raise any constitutional issues you will be handed your head and told that the court does not have subject matter jurisdiction. More likely than not the "judge" will give the government a summary judgment in its favor, with plenty of sanctions and penalties thrown in.
Also keep in mind that many tax court judges are former IRS agents. They put on batsuits and preside with all the trappings of an impartial forum with respect for the law and the Bill of Rights, but it is no such thing.
Tax courts were not created under Article III of the U.S. Constitution. Tax court was created to give ordinary Americans the illusion that they are getting justice under the current tax system. It's a sham and a direct descendent of the "star chambers" of the English monarchy.