The classes of taxable income are as follows:
For the purpose of this act, for the determination of the basis of any property, real and personal, if acquired prior to June 1, 1971, the date of acquisition shall be adjusted to June 1, 1971 as if the property had been acquired on that date. If the property was acquired after June 1, 1971, the actual date of acquisition shall be used in determination of the basis.
The term "net gains or income" shall not include gains or income derived from obligations which are statutorily free from State or local taxation under the laws of the taxpayer's State of residence or under the laws of the United States.
N.J.S. § 54:8A-73