Minimum - 5 years from the date of initial registration.
Extends automatically as long as the student does not fail to appear at two consecutive attempts.
Registration will lapse immediately after 5 years if the student has failed to appear in at least one of the last two examinations conducted just before the end of five years.
Revalidation
A student whose registration gets lapsed will be eligible for re registration. Such students can re-register himself/herself by paying a revalidation fee, which at present is Rs.500/-.
Application for Re-registration can be downloaded from the ICAI web site.