My 17 year old Daughter was diagnosed with Autism around the age of 5. She can never live alone. Is she considered disabled?

Yes, and if she's receiving SSI and the IRS asks you to prove her disability. Her awards letter with your name above hers will verify it. 

Yes, if your daughter has a physicians statement or is receiving SSI disability, she is disabled.

Per IRS: Child with Disabilities – You may be able to claim a child who is any age and permanently and totally disabled if the child meets the relationship test and all other tests to be your qualifying child for purposes of the EITC. The IRS considers a child permanently and totally disabled if both of the following are true:

1. The child cannot engage in any substantial gainful activity because of a physical or mental condition.
2. It is medically determined that the condition has lasted or can be expected to last continuously for at least a year or to lead to death.

For more information, see our page, Disability and the Earned Income Tax Credit.

Disabled for tax purposes has a very specific meaning. It means that a person is unable to perform substantial gainful work due to a condition that is permanent or that will last at least one year or that will lead to death.

this means that many people who have physical disabilities that would be recognized by a doctor are not disabled for income tax purposes as long as they can still work.  

The ability to work a minimum wage job with minimal special accommodations is considered by the IRS as proof that a person can perform substantial gainful work. However, work in a sheltered workshop for people with disabilities is not considered substantial gainful work even if the person gets paid.

So the question is not whether your daughter has a diagnosis or whether your daughter can live alone, the question is whether your daughter can perform gainful employment.  If your daughter can’t perform substantial gainful work, then you can indicate that she is disabled on the tax return and that will give you certain additional benefits as described by the other expert.