All of the following are requirements of eligibility for social security disability income benefits except:

The eligibility requirements for Social Security Disability Income (SSDI) benefits specify that applicants must meet certain criteria, one of which is related to their age. Specifically, individuals must be under the age of 65 to qualify for SSDI benefits; if a person is 65 or older, they would instead be eligible for retirement benefits.

The work history condition requires that individuals have a sufficient number of work credits, which is based on their employment history, ensuring they have contributed to the Social Security system through payroll taxes. Alongside this, applicants must have a qualifying medical condition that significantly impairs their ability to perform substantial gainful activity.

Therefore, being 65 years or older does not satisfy the SSDI eligibility requirements, making it the correct answer to identify as the exception.