Contact the Office of Attorney General's Child Support Office (OAG) and get a register of all payments made by the obligor. You can print this from the OAG's web site.
Make a spreadsheet of all the payments that SHOULD have been made, including date due, amount due, date paid, amount paid. Fill in the date and amount due based on the child support order. Fill in the date paid and amount paid based on the register of payments you get from the OAG web site.
When you fill in your spread sheet, credit payments according to when the payment was due, not when it was paid. For example, if you have 4 rows in your spreadsheet showing that a payment of $225 was due on 1/1/10, 2/1/10, 3/1/10, 4/1/10, and 5/1/10 and the registry of payments shows the first payment as made on 5/15/10, put that payment in the first row. In this case, your first row would say Payment Due: 1/1/10, Amount Due: $225, Payment Made: 5/15/10, Payment Amount: $225.
Get a list of missing Payments and Compute the Arrearage
Add up all of the payments that have been made and subtract that from the total of all the payments that were due. That difference is the ARREARAGE.
Your list of payments that are missing would be all the payments where the "Date Paid" column of your spreadsheet is blank OR the "Amount Paid" column is less than the "Amount Due" column.
Draft the Motion to Enforce Child Support
At this point, you really need to hire an attorney. If you can't afford one, you should contact the OAG and ask for their help in enforcing child support. They will help you, but they are not fast. If you just can't wait, go to the county law library, which will be in the courthouse, and get a form for child support enforcement. Beware of forms you can buy online or at the book store. Most of them are junk.
When you draft your motion or fill in the form, you will need a copy of the order that creates the child support obligation, the list of missing payments, and the amount of the arrearage, which you gathered above.
Be certain that your motion asks for a hearing date.
Get Ready to File Your Motion
Print 3 copies of your motion and sign each one. Print 3 copies of the registry of payments from the OAG web site. Attach one copy of the payment registry to each copy of your motion. Write down the obligor's work and home address. Take all this to the district clerk's office along with a check so you can pay the filing fee.
Finally, prepare an envelope addressed to yourself, and put two stamps on it.
If you can't afford the filing fee, fill out an Affidavit of Inability to Pay Court Costs and sign it in front of a notary. Bring two copies of it as well. If you file the affidavit along with the petition, you will not be charged a filing fee. HOWEVER, county governments are strapped for cash these days, so you should expect the district clerk to appear at your first hearing to challenge your inability to pay.
File Your Motion
Hand all copies of your motion to the district clerk. The clerk will stamp your motion and hand part of it back. At that point, if the clerk has not already noticed, point out that you are asking for citation and notice. Tell the clerk you want the constable to serve the obligor.
At that point, the way you get your motion set for a hearing differs from county to county. Just ask the clerk what you need to do to get a hearing set. The clerk may tell you to leave all your copies at the clerk's window so they can get the hearing date for you and notify you afterwards. If so, that's when you're self-addressed envelope will come in handy.
Serve the Obligor
The constable should serve the obligor for you. Depending on how hard the obligor is to locate, this might take a while. If the constable just can't do it for some reason, you will have to hire a private process server. They will know how to serve the obligor and when/how to seek substitute or alternative service.
Prepare An Order
While the constable's office is going it's job, prepare an order in your matter. Ask the county law librarian for a form of order confirming an arrearage. Fill in the form of the order and make 4 copies of it. This is the order the judge will sign on your hearing date.
Check on Service
Periodically, check to see if the obligor has been served. Many large counties have web sites that you can use for this purpose. Some counties require that you come to the clerk's office and look it up on computers in the clerk's office. Once the obligor has been served, get a certified copy of the Return of Service. If you end up hiring a private process server, ask the private process server for a copy of the return of service. This document proves to the court that the obligor was served.
Appear at Your Hearing
Bring your copy of your motion, all four copies of your proposed order, and the return of service with you. When you get to the courtroom, check in with the bailiff so he or she knows you are there. When the court calls your case, say, "May I approach, your honor?" The court will say "Yes". At that point, walk up to the bench, introduce yourself ("Good morning, your honor. I am John Doe and I am the petitioner in this child support enforcement matter.") At that point, the Judge will take over. If the obligor does not appear at the hearing, show the judge your return of service proving the obligor was duly and properly served. Then hand the judge ONE copy of your proposed order. The judge may sign your order right there but might also make changes to it. If the judge makes changes, make the exact same changes to your other 3 copies and then ask the judge how to get conformed copies (that process varies court by court, but usually the bailiff will conform your copies right then.