Allegedly the only criteria for being considered for nomination is that it has to be 25 years since the release of the act's first record. After that it's the personal whims of the nominating committee.
Induction Process | The Rock and Roll Hall of Fame and Museum
The Categories
Performers
Artists become eligible for induction 25 years after the release of their first record. Criteria include the influence and significance of the artists’ contributions to the development and perpetuation of rock and roll.
The Foundation’s nominating committee selects nominees each year in the Performer category. Ballots are then sent to an international voting body of more than 600 artists, historians and members of the music industry. Those performers who receive the highest number of votes - and more than 50 percent of the vote - are inducted. The Foundation generally inducts five to seven performers each year.
Ahmet Ertegun award
Songwriters, producers, disc jockeys, record executives, journalists and other industry professionals who have had a major influence on the development of rock and roll. (Please note that in 2011, the Ahmet Ertegun Award has replaced the Non Performer category.)
Early Influences
Artists whose music predated rock and roll but had an impact on the evolution of rock and roll and inspired rock’s leading artists.
The special selection committee elects the inductees in the Non-Performer and Early Influences categories.
Rock and Roll Hall of Fame Award for Musical Excellence
This category was introduced in 2000. It honors those musicians, producers and others who have spent their careers out of the spotlight working with major artists on various parts of their recording and live careers. Though they often play a key role in the creation of memorable music, the public rarely knows them by name. A separate committee selects the inductees in this category. (Please note that in 2011, the Rock and Roll Hall of Fame Award for Musical Excellence has replaced the Sidemen category.)