(a) Amount of credit

For purposes of section 38, the amount of the Indian employment credit determined under this section with respect to any employer for any taxable year is an amount equal to 20 percent of the excess (if any) of-

(1) the sum of-

(A) the qualified wages paid or incurred during such taxable year, plus

(B) qualified employee health insurance costs paid or incurred during such taxable year, over

(2) the sum of the qualified wages and qualified employee health insurance costs (determined as if this section were in effect) which were paid or incurred by the employer (or any predecessor) during calendar year 1993.