Section 11-643. Computation of tax for taxable years ending on or before December thirty-first, nineteen hundred seventy-three

For taxable years  ending  on   or   before   December   thirty-first,   nineteen   hundred
  seventy-three,  the  tax imposed by section 11-639 of this part shall be
  the greater of the following computations:
    (a) Basic tax. Five and  sixty-three  one-hundredths  percent  of  the
  taxpayer's  entire  net income, or the portion thereof allocated to this
  city, for the taxable year or part thereof. (b) Alternative minimum tax.
  If the tax under subdivision (a) is  less  than  any  of  the  following
  amounts, the tax shall be the largest of the following amounts:
    (1)  Except  for  a savings bank and savings and loan association, one
  and one-quarter mills upon each dollar of such part  of  the  taxpayer's
  issued  capital  stock  on the last day of the taxable year, at its face
  value, but if such taxpayer has stock  without  par  value,  such  stock
  shall  be  taken  at  its actual or market value, and not less than five
  dollars per share, as may be determined by the commissioner of  finance,
  as  the  gross  income of such taxpayer derived from business carried on
  within the city, during such taxable year, bears  to  its  gross  income
  derived  from all business, both within and without the city during said
  year; except that if the period covered by  the  return  is  other  than
  twelve  months,  the tax shall be prorated on the basis of the number of
  months or major portions thereof included in the return. For purposes of
  this paragraph, the term "gross income" shall have the same  meaning  as
  it  has  in  the  laws  of  the United States relating to federal income
  taxes.
    (2) For a savings bank and  savings  and  loan  association,  one  and
  forty-three one-hundredths percent of the interest or dividends credited
  by  it  to  depositors or shareholders during the taxable year, provided
  that, in determining such amount, each interest or dividend credit to  a
  depositor  or shareholder shall be deemed to be the interest or dividend
  actually credited or the interest or  dividend  which  would  have  been
  credited  if  it had been computed and credited at the rate of three and
  one-half percent per annum, whichever is less.
    (3) Twelve and one-half dollars.