The extended period of eligibility, SSDI eligible, is a period of thirty six months following the Trial Work Period or TWP when, if the claimant qualifies, the Social Security will restart SSDI benefits without a new application, disability determination or waiting period. The first 36 months of the Extended Period of Eligibility is the re-entitlement period. During the re-entitlement period, benefits are paid for months a claimant's earnings or work activities are below the substantial gainful activity level as long as he continues to have a disabling impairment.