Pursuant to Nebraska statute (Neb. Rev. Stat. 42-371.01), child support ends on the child's birthday - so that is the actual date and the amount that should be paid is prorated from the full month's amount. So if the child's birthday is XXXXX 15th, you would be paid for 15 of 30 days or 1/2 the month ($250).
Hope this helps.
§ 42-371.01. Duty to pay child support; termination, when; procedure; State Court Administrator; duties
(1) An obligor's duty to pay child support for a child terminates when (a) the child reaches nineteen years of age, (b) the child marries, (c) the child dies, or (d) the child is emancipated by a court of competent jurisdiction, unless the court order for child support specifically extends child support after such circumstances.
(2) The termination of child support does not relieve the obligor from the duty to pay any unpaid child support obligations owed or in arrears.
(3) The obligor may provide written application for termination of a child support order when the child being supported reaches nineteen years of age, marries, dies, or is otherwise emancipated. The application shall be filed with the clerk of the district court where child support was ordered. A certified copy of the birth certificate, marriage license, death certificate, or court order of emancipation or an abstract of marriage as defined in section shall accompany the application for termination of the child support. The clerk of the district court shall send notice of the filing of the child support termination application to the last-known address of the obligee. The notice shall inform the obligee that if he or she does not file a written objection within thirty days after the date the notice was mailed, child support may be terminated without further notice. The court shall terminate child support if no written objection has been filed within thirty days after the date the clerk's notice to the obligee was mailed, the forms and procedures have been complied with, and the court believes that a hearing on the matter is not required.
(4) The State Court Administrator shall develop uniform procedures and forms to be used to terminate child support.