“Once the mother has exonerated the father from child support and he’s received the papers stating such from the Attorney General’s office in Texas, can she suddenly decide to apply for support and change her mind even though there’s no custody or visitation agreement of any kind?”
At any time, any parent can file for custody and/or support. A court order or ruling on the case will stand against any other outside documentation on the situation. And, in fact, in many jurisdictions a custodial parent cannot, under the law, legally waive child support, as those monies are for the child’s benefit, not the parent’s. What this means is that if there is an out-of-court agreement to forego child support, the court cannot uphold it. If the parties cannot come to an agreement outside of Court, and wish to formalize the agreement, it may be in your best interests to contact an attorney who practices family law in your jurisdiction.