The AK Permanent Fund Dividend is the only income for my disabled adult (20 years old) dependent child. Must he file a return? Do I report his this on my taxes ( 8814)?

Your dependent adult child will not need to file a return for his Alaska Permanent Fund Dividend if it is under $1,050. If he were not your dependent, it would not be required if it is under the filing limit of $10,350 for a single adult.   You will not need to file Form 8814 for "kiddie tax" if your child was over age 19 and not a full-time student.

Thanks.

You said the person is a dependent.  That changes things.

Assuming that is his only income, he must file a tax return if his unearned is over $1050.

https://www.irs.gov/publications/p17#en_US_2017_publink1000170430

From what I can see, the Alaska PFD was $1100, which would mean he is required to file a tax return.  Unless he was a full-time student, Form 8814 can not be used, so he needs to file his own tax return.

Thanks, that's what I thought.