Child support modification is one of the few places in Texas family law where the legislature gave you a genuinely simple path, and hardly anybody uses it. Most people assume they have to prove a material and substantial change, they can’t figure out how to prove one, and they never file.
There’s a second door, and for a lot of people it’s wide open.
The two ways in
Under Texas Family Code § 156.401, a court can modify a child support order if either of two things is true.
The first is the one everybody knows. The circumstances of the child, or of a person affected by the order, have materially and substantially changed since the order was rendered, or since the date a mediated or collaborative settlement agreement the order was based on was signed. That’s the general standard, and it’s fact-dependent and arguable.
The second is mechanical, and it’s the one I want you to focus on. If it has been three years since the order was rendered or last modified, and the current monthly support amount differs by either 20 percent or $100 from what the guidelines would produce today, you can modify. That’s it. No proving anybody’s circumstances changed. You run the guideline calculation, you compare it to your order, and if the gap clears either threshold, you qualify.
Read that as either, not both. A $100 difference is enough on its own, and on a modest support order $100 a month is not a large gap. A lot of three-year-old orders clear that bar without anybody’s life having dramatically changed at all.
Why more orders qualify than people think
Guideline support in Texas is calculated on the obligor’s monthly net resources, applying a percentage that depends on how many children are before the court and how many other children that parent supports. Wages move, second jobs come and go, health insurance premiums change, and the number of children in the calculation changes as kids age out. Any of that can shift the guideline number without feeling like a “material and substantial change” to the person living it.
There’s also a change on the books worth knowing about. Guideline support applies to net resources up to a cap, and that cap is adjusted periodically. It moved to $11,700 per month effective for orders entered on or after September 1, 2025, up from $9,200. If your order predates that and the obligor’s income is above the old cap, nothing updates automatically. Somebody has to file.
I’ve written separately about how child support is actually calculated in Texas, and I’d run those numbers before you do anything else, because the whole three-year analysis depends on knowing what the guideline amount would be today.
The incarceration provision
One specific rule worth flagging, since it comes up more than you’d expect. The statute provides that incarceration of a child support obligor in a local, state, or federal jail or prison for a period exceeding 180 days is a material and substantial change of circumstances for purposes of modification. That cuts in an obvious direction, but it’s written into the statute rather than left to argument, and people on both sides of that situation should know it’s there.
The Attorney General versus filing it yourself
You’ve got two routes, and they suit different people.
The Office of the Attorney General runs a child support review process, and it costs you nothing. If your case is straightforward, if you’re not in a hurry, and if there’s no real dispute about income, that’s a perfectly reasonable path and I’ve told plenty of people to use it. The tradeoffs are that it’s slow, sometimes very slow, you don’t control the timeline, and the OAG represents the State’s interest in the support order rather than representing you. If there’s a fight about what the obligor actually earns, or if self-employment income is involved, the OAG process often isn’t equipped to dig the way your case needs.
Filing your own modification puts you in control of the pace and lets you use discovery to get at income the other side would rather not discuss. That matters enormously when you’re dealing with someone who’s self-employed, paid partly in cash, or suddenly and conveniently underemployed. If that’s your situation, understand that Texas courts can set support on earning potential rather than actual earnings when a parent is intentionally unemployed or underemployed, and that’s a fight worth having with real evidence behind it.
A word about timing and retroactivity
File when you become eligible rather than waiting for a better moment, because as a general matter a modification reaches back to when the motion was filed and served, not to when the circumstances actually changed. Every month you sit on it is a month at the old number that you don’t get back.
That single piece of advice has been worth thousands of dollars to people I’ve worked with, and it costs nothing to follow. If you think you qualify, run the numbers this week.
And one last thought for the parent on the paying side, because this cuts both ways. If your income has genuinely dropped, the order does not adjust itself because your circumstances changed. Unpaid support keeps accruing at the ordered amount, and it accrues interest, and you cannot go back later and undo the arrears that piled up while you were waiting to see if things turned around. File.
I’m not an attorney and this isn’t legal advice. I’m a coach who helps pro se litigants in Texas family law cases understand the process and prepare their own case. If you want to know whether your order qualifies for modification, let’s run the numbers together.