28 C.F.R. § 542.18
If accepted, a Request or Appeal is considered filed on the date it is logged into the Administrative Remedy Index as received. Once filed, response shall be made by the Warden or CCM within 20 calendar days; by the Regional Director within 30 calendar days; and by the General Counsel within 40 calendar days. If the Request is determined to be of an emergency nature which threatens the inmate's immediate health or welfare, the Warden shall respond not later than the third calendar day after filing. If the time period for response to a Request or Appeal is insufficient to make an appropriate decision, the time for response may be extended once by 20 days at the institution level, 30 days at the regional level, or 20 days at the Central Office level. Staff shall inform the inmate of this extension in writing. Staff shall respond in writing to all filed Requests or Appeals. If the inmate does not receive a response within the time allotted for reply, including extension, the inmate may consider the absence of a response to be a denial at that level.
28 C.F.R. § 542.18