When can you modify child support in Texas?

Texas allows a child support modification when circumstances have materially and substantially changed, or when it has been three years since the order and the guideline amount differs by 20% or $100 from the current amount.

How to Modify a Texas Child Support Order

Written and kept current by Donald C. Nemec, a Texas family-law attorney (State Bar of Texas No. 24049967) with 18 years in Texas courts. Last reviewed against the Texas Family Code on May 16, 2026.

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A child support order is not permanent. When life changes, Texas Family Code § 156.401 lets either parent ask the court to change the amount.

The two ways to qualify

A court can modify child support if either of these is true:

Material and substantial change. The circumstances of the child or a parent have materially and substantially changed since the order — for example, a significant change in income, a job loss, a new child to support, a change in the possession schedule, or a major change in the child's medical or educational needs.
The 3-year / 20% rule. It has been three years since the order was set or last modified, and the amount under today's guidelines would differ from the current order by 20% or $100.

How to estimate whether it's worth filing

Run the current numbers through the child support calculator. If today's guideline figure is meaningfully different from what the order says, a modification may be worth pursuing.

The steps

File a petition to modify in the court that has jurisdiction over the order (usually the county that issued it).
Serve the other parent with notice.
Exchange financial information — recent pay records, tax returns.
Negotiate or attend a hearing. Many modifications settle by agreement; contested ones go before the judge.
The court signs a modified order.

Important: support changes only from the filing date

A modification generally takes effect back to the date the petition was filed — not the date circumstances changed. Waiting to file means losing money. If your income drops, file promptly; missed payments under the old order still accrue until the court changes it.

Frequently asked questions

Can we just agree to a new amount without going to court? An informal agreement is risky — it is not enforceable and back support can still be claimed under the old order. Put any change in a new court order.

Can child support be modified through the Attorney General's office? Yes. The Texas OAG Child Support Division offers a review and adjustment process, though it can be slower than filing directly.

This is general information, not legal advice. For help filing or responding to a modification, contact Nemec Law Office, serving Tarrant, Dallas, Denton, and Collin counties.