Separate service member and civilian contributions.
CFR · 2024-01-01 · US · Title 5
The TSP record keeper maintains uniformed services accounts separately from civilian accounts. Therefore, a participant who has made contributions as a uniformed service member and as a civilian employee will have two TSP accounts: A uniformed services account and a civilian account.
official document · source cfr-2024 · id 5:§ 1600.18