Can woman have tapered or undercut hair while in basic training?

Female hair cannot be shorter than 1/4”, as long as the shortest part is no less than 1/4” it will be fine. By the way a #2 on the clippers is 1/4”. I currently sport an undercut, #2 on sides and back, and about 4 inches on top.

Google AR670-1 defines the hair styles authorized by the Army. It can be googled or go to Army G1 and search The AR above.

Per TRADOC 350-6, female trainees may shave their hair down to 1/4" at a minimum, and may wear any conservative hairstyle that does not interfere with the proper wear of the uniform, or may be perceived as "faddish."