From Amanda Cox <amandacox@usarugby.org>:

Any referee who wishes to be considered for National Assignments in Fall of 2017 should submit a passing fitness test score by September 1. The YoYo test is preferred, but the Beep test will be accepted until the 2018 cycle.

Fall 2017 Passing Fitness Scores
Grade   YoYo    Beep
Elite   18.5    12.6
NP      18      12
B       17      11
C1      17      11
C2      16      10