is support required after child turns 18, filing requirements or court order needed to continue support after 18 years

Your question depends on what state you live in and the status of the 18 year old. Most states have a provision for child support to continue past the age of 18 under various circumstances, the first of which is that the child is still in high school and the second is if the child has any mental or physical disabilities that would impair their ability to care for themselves. You will need to file a petition in your local courthouse to have the support continue. You should talk to a local attorney and find out what the local laws are in relation to child support.

The answer to this question is completely dependent on the state where the controlling support order was issued.