Incomes change, jobs change, kids' needs change. Texas lets you ask the court to raise or lower an existing child support order — but only when you meet one of two specific grounds in Family Code §156.401. Here are both grounds with real numbers, the two ways to file, and the timing rule that quietly decides how much a modification is worth.
The two ways to qualify
1. A material and substantial change
You can seek modification if the circumstances of the child or a person affected by the order have materially and substantially changed since it was last set. The comparison point is your situation on the day the current order was signed. Common examples:
- A significant, lasting increase or decrease in either parent's income
- A change in who the child lives with, or the possession schedule
- New medical needs or child-care costs
- The paying parent becoming legally responsible for additional children
- Incarceration of the paying parent for more than 180 days (treated as a material change)
The change generally needs to be real and durable — a slow month or a short gap between jobs usually won't carry a modification on its own.
2. The three-year / 20%-or-$100 rule
Even without a dramatic change, you can request modification if three years have passed since the order was set or last modified and the amount under the current guidelines would differ from the existing order by 20% or $100. This route exists so orders don't drift too far from reality as incomes move.
The 20% / $100 test in real numbers
Say your order was set three years ago at $518/month — the guideline figure for one child when you were grossing $3,000/month as a single W-2 employee. You now gross $5,000/month, where the guideline amount is about $840/month. The gap is $840 − $518 = $322, which clears both prongs comfortably: it's more than $100, and it's well over 20% of the existing order (20% of $518 ≈ $104). Either prong alone is enough — the statute says 20% or $100.
The same arithmetic works in reverse. A parent ordered to pay $840 whose gross income falls from $5,000 to $3,000 would see a current guideline figure near $518 — the same $322 difference, this time supporting a decrease. The income chart shows guideline amounts across the range, and the net-resources guide explains how gross pay becomes the "net" figure the percentages apply to.
The mistake that costs people thousands
Child support does not change on its own when your situation changes. If you lose your job and simply stop paying, the original amount keeps accruing — plus interest — until a court signs a new order, and Texas law is unusually strict here: under §157.008, a court cannot retroactively reduce support that has already come due. A modification generally reaches back at most to the date the other parent was served with the petition — not to the day you were laid off, and not to the day you meant to file.
The practical takeaway: every month between the change and the date of service is locked in at the old amount, forever. File promptly and keep paying what you can meanwhile. The enforcement guide covers what happens to a balance you let build instead — none of it good.
Two ways to file: OAG review or court petition
Texas gives you two paths to the same destination — a new signed order:
| OAG review (CSRP) | Court petition | |
|---|---|---|
| Cost | Free — the Attorney General's Child Support Division reviews the order at no charge | Filing fees, plus attorney's fees if you hire one |
| How it works | Administrative review; eligible cases go through the Child Support Review Process, a negotiation meeting that can produce an agreed order | Petition to Modify filed in the court that issued the order, with formal service and, if needed, a hearing |
| Best for | Straightforward guideline recalculations where both parents will participate | Contested cases, complex income, or situations where timing and strategy matter |
| If you disagree | The case moves to court anyway | A judge decides at a hearing |
Neither route has a fixed timeline — an agreed CSRP order can come together far faster than a contested court fight, and both depend on caseloads and dockets. That uncertainty is one more reason the date-of-service rule rewards filing early.
How the process works
- File a Petition to Modify in the court that issued the current order — or ask the OAG Child Support Division to review the case instead.
- Serve the other parent so they have formal notice. This date matters: it's usually the earliest day a new amount can reach back to.
- Exchange financial information — recent pay stubs, tax returns, and proof of whatever changed.
- Agree or go to a hearing — many cases settle once both sides see the guideline math; otherwise a judge decides.
- Get a signed order — only the new signed order changes what's owed, and only it updates the wage withholding your employer follows.
Common mistakes to avoid
- Waiting to file. Because the new amount reaches back only to service, every month of delay is paid at the old rate — permanently.
- Stopping payment while the case is pending. The old order controls until it's replaced. Unpaid months become arrears with interest, and §157.008 blocks a judge from erasing them later.
- Relying on a handshake deal. An informal "we agreed to less" is not enforceable. Wage withholding keeps running at the old figure, and if it isn't paid, the shortfall accrues on paper regardless of what the other parent said.
- Counting a new spouse's income. A step-parent's earnings are not part of net resources — remarriage alone doesn't move the guideline number in either direction.
- Quitting or downshifting to shrink the number. If a court finds a parent intentionally unemployed or underemployed, it can set support on earning potential rather than actual income (§154.066) — see the unemployment guide.
Frequently asked questions
How long does a modification take?
It varies — genuinely. An agreed recalculation through the CSRP can wrap up quickly; a contested court case takes as long as the docket demands. What doesn't vary is the retroactivity rule: however long it runs, the result generally reaches back only to the date of service.
Can support be modified retroactively?
Only back to the date the other parent was served with the modification petition, and no earlier. Amounts that came due before that date stay owed at the old figure — §157.008 bars retroactive reduction, which is why arrears that built up before you filed don't shrink when the new order arrives.
Is the OAG review really free?
Yes. Either parent can ask the Attorney General's Child Support Division to review an order at no cost, and eligible cases proceed through the Child Support Review Process without a contested hearing. The trade-off is pace and control — and if the parents can't agree, the case ends up in court anyway.
Can we just agree to a new amount informally?
You can agree on anything — but until a judge signs it, the existing order is the only thing with legal force. If the agreed amount is lower and the difference goes unpaid, it accrues as arrears. Put the agreement in front of the court and make it an order.
Does remarriage change child support?
Not by itself. A new spouse's income is excluded from net resources, so remarriage doesn't raise or lower the guideline amount. What can matter is a new child you're legally obligated to support — that triggers the multiple-family adjustment, which lowers the percentage applied to the children before the court.
Will another baby lower my payment?
It can, through the multiple-family guideline (§154.129) — a parent supporting children in more than one household pays a lower percentage than the standard schedule on the main chart. But the adjustment isn't automatic; you still have to seek modification.