Theft
1.
the act of stealing; the wrongful taking and carrying away of the personal goods or property of another; larceny.
2.
an instance of this.
3.
Archaic . something stolen.
(from dictionary.com)
Therefore, how can not paying taxes be theft? How am I taking money that belongs to somebody else if it’s my own money I’m keeping?
You are entitled to follow your Rav, but so am I. And my Rav holds cheating on your taxes is sheker, but not geniavah.