more details

https://www.rimtorim.org/hike-it/

* Day hikes and hikers staying at Phantom Ranch are not required to have permits.

* You only need a permit, which is where lottery drawing comes in, if you’re going to camp overnight in the Canyon.

* As of September 15, 2014 if you are with any group that publicly advertises a trip from rim to rim you will need a permit.  Any organized, noncommercial, group conducting rim-to-rim and extended day hiking and running, including rim-to-river-to-rim, and rim-to-rim-to-rim in the inner canyon is required to obtain a Special Use Permit from Grand Canyon National Park. The inner canyon is defined as the area below the Tonto Platform (Tipoff and Indian Garden) from the South Rim and below Manzanita Resthouse (Pumphouse Residence) from the North Rim. Any group, regardless of size, which has advertised to the general public, required individuals to sign up prior to participation, or that has an organizer who has been compensated for their services (including subsidized participation in the activity), is required to operate under a Special Use Permit. For more information visit www.nps.gov/grca/parkmgmt/sup.htm

To camp overnight in the Grand Canyon, you are required to have a camping permit. For the Rim to Rim they’re very competitive to secure, so plan on trying several times before getting a permit. Permits become available 4 months in advance. For example if you want to hike in October, you’d apply on June 1st. You fax your application in to the Backcountry Information Center. Information can be found on the NPS website.