Matching payment period means the period beginning January 1 of the calendar year in which a Presidential general election is held and may not exceed one of the following dates:

(a) For a candidate seeking the nomination of a party which nominates its Presidential candidate at a national convention, the date on which the party nominates its candidate.

(b) For a candidate seeking the nomination of a party which does not make its nomination at a national convention, the earlier of—

(1) The date the party nominates its Presidential candidate, or

(2) The last day of the last national convention held by a major party in the calendar year.