148.620.  Annual tax on net income, rate — credits allowed, exceptions. — 1.  Every taxpayer shall be subject to an annual tax for the privilege of exercising its corporate franchises within the state according to and measured by its net income for the preceding year.

  2.  The rate of tax for each taxable year shall be seven percent of such net income.

  3.  The tax imposed on the net income by this law shall be exclusive and in lieu of all other state and local taxes against and upon credit unions and associations, their capital, or income, except taxes on all property, contributions paid pursuant to the unemployment compensation law of Missouri, Social Security taxes, sales and use taxes.

  4.  Each taxpayer shall be entitled to credits against the tax imposed by this law for all taxes paid to the state of Missouri or any political subdivision thereof during the relevant income period, except taxes on real estate and tangible personal property owned by the taxpayer and held for lease or rental to others, contributions paid pursuant to the unemployment compensation law of Missouri, Social Security taxes, sales and use taxes, and taxes imposed by this law.