In The Politics of Autism, I write:
When disabled people reach their 22d birthday, they no longer qualify for services under IDEA. ... People in the disability community refer to this point in life as “the cliff.” Once autistic people go over the cliff, they have a hard time getting services such as job placement, vocational training, and assistive technology. IDEA entitles students to transition planning services during high school, but afterwards, they have to apply as adults and establish eligibility for state and federal help. One study found that 39 percent of young autistic adults received no service at all, and most of the rest got severely limited services.
At Current Psychiatry Reports
, Amanda Bennett and colleagues have an article titled "Autism Spectrum Disorder and Transition-Aged Youth." The abstract:
Purpose of Review
This article discusses common issues surrounding transition to adulthood in youth with autism spectrum disorder (ASD). We review recent evidence on co-occurring medical and mental health conditions and topics of education and employment, sexuality and relationships, independent living, and financial support.
Transitioning individuals with ASD have increased risk for several medical and behavioral health comorbidities and should be routinely screened for co-occurring conditions. Evidence on interventions for mental health disorders is limited but emerging, particularly with respect to mindfulness training and cognitive behavioral therapy. Many autistic adults or their families express a desire for independent living, participation in education/employment, and intimacy and social relationships, but they often lack skills and/or resources to successfully achieve these outcomes.
The time of transition to adulthood for adolescents with ASD is an opportunity for physicians to provide anticipatory guidance and necessary supports around issues of community participation. To allow time for planning, these discussions should occur well before the child reaches adulthood. Clinicians should also routinely screen for and address medical and/or behavioral health comorbidities.
From the article:
In US law and policy, there is increasing emphasis on improving transition outcomes in general, and employment specifically, for individuals with disabilities, including ASD. Since 1990, the Individuals with Disabilities Education Act has required that schools develop a transition plan (including plans for employment) for any student who has an individualized education plan (IEP) . Current federal law requires that the transition plan be developed by the time the child is 16 years of age, but some states require it to be done earlier. The Workforce Innovations and Opportunity Act of 2014 emphasized that VR [vocational rehabilitation] agencies need to work with employers to increase competitive employment outcomes for adults with disabilities.
Despite these federal rules, implementation of educational and VR policies varies greatly at the state (and local) level. In a study of outcomes of VR services across the US, it was found that only 36% of transition-aged (younger than 22 years of age) youth with ASD who received VR services between 2002 and 2011 were employed , but there was significant variability across states. In six states, more than half of the autistic young adults receiving services were employed, and in four states, less than 25% were employed. More recent data from those who received VR services in 2013 suggests some improvement, as over 56% were reported to have achieved competitive or supported employment . The VR services most consistently associated with employment are job placement and on-job supports, yet other services such as assessment services, counseling services, and job search services are more commonly provided .
A recent randomized trial suggests that even greater improvements in employment outcomes are possible when job placement and on-job supports are emphasized and coordinated services are provided across schools, VR, and employers . Wehman and colleagues  studied 49 students with ASD and an IEP who required moderate to high levels of support at baseline. Most of the students had academic skills below a third-grade level, but were able to independently dress, eat, and attend to personal hygiene . The intervention group received 9 months of training on-site at two suburban hospitals where they rotated through job internships and participated in classes, learning job skills and social communication behaviors [37, 42]. The control group received interventions as specified in the IEP through their high school. At 3 months postgraduation, 90% of individuals receiving the intervention compared to 5.9% of controls were competitively employed. At 12 months postgraduation, 87% of the intervention group and 11.1% of controls were employed. Young adults in the intervention group were working an average of approximately 19 h per week with an average wage over $8.00/h when the state’s minimum wage was $7.25/h [37, 42].
The Wehman et al.  study is unique in that it is a randomized trial, but other studies suggest that successful employment is possible for many adults with ASD. For example, in the study of state employment outcomes mentioned above, one VR service provider reported an 87% success rate in obtaining competitive employment for adults with ASD . Similarly, another study of 64 adults with ASD referred to VR for supported employment services found that 98% were successfully employed, although only 63% maintained their employment for more than 6 months .