I had a challenging time finding this information until I hit upon the right search phrase, so I thought I would publish a quick reference to Special Education Age Limits by State. This is one of the areas that is not mandated at the Federal Level, so if you are planning Transition services for your child, you need to know the age limits in your state.
The following information was gathered from a PDF published by the U.S. Department of Education on the Ages that Special Education Services are provided (by State). The end dates often include additional details. See the PDF or contact your State Department of Education for further information. https://www2.ed.gov/policy/speced/guid/idea/letters/2002-2/osep0206-2q2002.pdf
| State | Ages |
| AL | 3 through 20 |
| AK | 3 through 21 |
| AZ | 3 through 21 |
| AR | 3 through 20 |
| CA | 3 through 18 |
| CO | 3 through 20 |
| CT | 3 through 20 |
| DE | 3 through 20 |
| DC | 3 through 21 |
| FL | 3 through 21 |
| GA | 3 through 21 |
| HI | 3 through 19 |
| ID | 3 through 20 |
| IL | 3 through 20 |
| IN | 3 through 21 |
| IA | 3 through 20 |
| KS | 3 through 20 |
| KY | 3 through 20 |
| LA | 3 through 21 |
| ME | 3 through 19 |
| MD | 3 through 20 |
| MA | 3 through 21 |
| MI | 3 through 21 |
| MN | 3 through 20 |
| MS | 3 through 20 |
| MO | 3 through 20 |
| MT | 3 through 18 |
| NE | 3 through 20 |
| NV | 3 through 21 |
| NH | 3 through 20 |
| NJ | 3 through 21 |
| NM | 3 through 21 |
| NY | 3 through 20 |
| NC | 3 through 20 |
| ND | 3 through 20 |
| OH | 3 through 21 |
| OK | 3 through 21 |
| OR | 3 through 20 |
| PA | 3 through 20 |
| PR | 3 through 21 |
| RI | 3 through 20 |
| SC | 3 through 21 |
| SD | 3 through 20 |
| TN | 3 through 21 |
| TX | 3 through 21 |
| UT | 3 through 21 |
| VT | 3 through 21 |
| VA | 3 through 21 |
| WA | 3 through 20 |
| WV | 3 through 20 |
| WI | 3 through 20 |
| WY | 3 through 20 |