A thread milling tool includes a proximal shank portion and a distal cutting portion. The cutting portion includes at least one thread milling tooth and at least one flute oriented helically, or spirally, about a central rotational axis of the tool. The cutting portion may be configured to form internal or external threads in a workpiece as the cutting portion moves relative to the workpiece. The teeth of the thread milling tool have a negative taper angle or back taper to offset deflection of the tool during milling operations.