(a) Contribution elections. A contribution election must be made pursuant to § 1600.12 and includes the following types of elections:

(1) To make employee contributions;

(2) To change the amount of employee contributions;

(3) To change the type of employee contributions (traditional or Roth); or

(4) To terminate employee contributions.

(b) Investment election. A participant may make or change the manner in which future deposits to his or her account are allocated among the TSP core funds only in accordance with 5 CFR part 1601.