1. (a) The average number of employees employed in the economic development zone or, where applicable, in the geographic area subsequently constituting such zone, in a taxable year as used in this Subpart is computed as follows:

   1. (1) ascertain the number of employees within the economic development zone, designated pursuant to article 18-B of the General Municipal Law, or where applicable, in the geographic area subsequently constituting such zone, except general executive officers, employed by the taxpayer on March 31st, June 30th, September 30th, and December 31st in the taxable year;
   2. (2) add together the number of such employees ascertained on each of such dates; and
   3. (3) divide the sum by the number of such dates occurring within the taxable year.
2. (b) In the case of a taxpayer having a short taxable year which does not include any of the dates set forth in paragraph (a)(1) of this section, the number of employees within such economic development zone employed by the taxpayer on the last day of such taxable year shall constitute the average number of employees for such taxable year.
3. (c) For purposes of this Subpart, the term employees and the term general executive officers have the same meanings as in Subpart 4-5 of this Title. Payroll factor of business allocation percentage.

Tax Law, § 210(12-C)(b)