The amount of savings bonds of Series I which may be purchased and held, in the name of any one person in any one calendar year, is computed according to the provisions of § 360.11 and is limited as follows:

(a) General annual limitation, $5,000 (par value).

(b) Special limitation, $4,000 (par value) multiplied by the highest number of employees participating in an eligible employee plan, as defined in § 360.13, at any time during the calendar year in which the bonds are issued.