43 CFR § 3836.26
How long may a deferment of assessment work last?
June 11, 2020
(a) BLM may grant a deferment for up to one assessment year. However, the deferment ends automatically if the reason for the deferment ends.
(b) The deferment period will begin on the date you request in the petition unless BLM's approval sets a different date.
(c) You may petition to renew the deferment for one additional assessment year if a valid reason for a deferment continues. BLM cannot renew your deferment of assessment work more than once.