It is on certain business activities and on certain privileged occupations. Again, the Supreme Court, Congress and the IRS have all stated this in writing a number of times. Third, the 16th Amendment DID NOT allow an income tax. One of the possible sources of income is your personal paycheck. Trading your labor or knowledge for a paycheck is NOT a taxable event, according to several Supreme Court cases.
All income derived from a revenue taxable activity is subject to the income tax.
Ask that same tax professional what activity YOU are engaged in that is subject to revenue taxation. Wake up, America. If you are a Free-Market. The ignorance is extremely obvious on this board. The Supreme Court has stated this no less than 6 times, the Congress no less than 3 times and the IRS no less than 6 times.