When Can Child Support Be Modified?
Child support orders are not necessarily permanent. As children grow, parents change employment, incomes fluctuate, and financial circumstances evolve, the law recognizes that an existing child support order may no longer reflect the realities facing the family. For that reason, Texas courts retain continuing jurisdiction to modify child support under appropriate circumstances. Modification proceedings are governed primarily by Chapter 156, Subchapter E of the Texas Family Code, while the calculation of child support remains governed by the guidelines contained in Chapter 154 of the Texas Family Code.

A court may not modify child support simply because one parent believes the existing amount is unfair or wishes to revisit the original order. Instead, the party requesting modification bears the burden of proving that the statutory requirements for modification have been satisfied. The trial court must then determine whether the requested modification is consistent with the child's best interests.

Section 156.401 of the Texas Family Code establishes two independent statutory grounds upon which child support may be modified. First, the court may modify support if the circumstances of the child or a person affected by the order have materially and substantially changed since the prior order was rendered. Second, modification may be appropriate when at least three years have elapsed since the order was rendered or last modified and the monthly child support obligation differs from the amount that would be awarded under the current child support guidelines by either twenty percent or one hundred dollars. Either basis may authorize the court to reconsider an existing child support obligation.

Material and Substantial Change
The most frequently asserted ground for modification is a material and substantial change in circumstances. Although the Texas Family Code uses this standard throughout Chapter 156, it does not define precisely what constitutes a material and substantial change. Instead, Texas appellate courts have consistently held that the trial court compares the circumstances existing when the previous child support order was entered with the circumstances existing at the time of the modification hearing.

Whether a particular change satisfies this standard depends upon the facts of each individual case. A substantial increase or decrease in a parent's income may justify modification. Likewise, the loss of employment, the onset of a disability, significant changes in the child's medical or educational needs, or other meaningful changes affecting the financial circumstances of the parties may warrant judicial intervention. Conversely, relatively minor fluctuations in income or ordinary changes associated with the passage of time may not constitute the type of material and substantial change contemplated by the statute.

Because the inquiry is highly fact-specific, trial courts are afforded considerable discretion in determining whether the evidence demonstrates a sufficient change in circumstances. Texas appellate courts generally review those decisions under an abuse of discretion standard.

The Three-Year Rule
Not every modification requires proof of a material and substantial change.

Section 156.401(a)(2) provides an alternative method of modifying child support. Under that provision, a court may modify support if at least three years have passed since the existing order was rendered or last modified and the amount that would be awarded under the current child support guidelines differs from the existing monthly obligation by either twenty percent or one hundred dollars.

This provision reflects the Legislature's recognition that support orders may gradually become inconsistent with the guideline calculations as parental income changes over time, even if no single event constitutes a material and substantial change.

The three-year provision does not apply in every case. When parents previously entered into an agreed child support order that intentionally varied from the guideline amount, Section 156.401(a-1) generally requires proof of a material and substantial change before the agreed amount may be modified. The Legislature has therefore distinguished between support orders imposed under the guidelines and negotiated agreements in which the parties intentionally deviated from the presumptive amount.

Are Texas Judges Required to Follow the Child Support Guidelines?
The Texas child support guidelines are often described as mandatory, but that description is incomplete.

Chapter 154 establishes a rebuttable presumption that the guideline amount is in the child's best interest. The guidelines therefore provide the starting point for the court's analysis rather than an inflexible rule that applies in every case.

Section 154.123 expressly authorizes a trial court to deviate from the guideline amount when application of the guidelines would be unjust or inappropriate under the particular facts presented. In deciding whether a deviation is warranted, the court may consider numerous statutory factors, including the child's proven needs, the financial resources of both parents, extraordinary medical or educational expenses, significant travel expenses associated with possession, periods of possession substantially exceeding the standard possession schedule, and other equitable considerations recognized by the statute.

When a court orders child support that differs from the guideline calculation, the Family Code generally requires findings explaining why application of the guidelines would be inappropriate and why the amount ordered nevertheless serves the child's best interest.

The Trial Court Retains Broad Discretion
Although the Family Code provides detailed statutory guidance, child support modification remains an equitable proceeding entrusted to the sound discretion of the trial court.

In Rodriguez v. Rodriguez, 860 S.W.2d 414 (Tex. 1993), the Texas Supreme Court reaffirmed that trial courts possess broad discretion in determining child support issues. Likewise, in Iliff v. Iliff, 339 S.W.3d 74 (Tex. 2011), the Court emphasized that the child's best interest remains the paramount consideration in child support proceedings and discussed the circumstances under which earning capacity may be considered when calculating support.

Texas appellate courts have also consistently held that the existence of a material and substantial change is determined by comparing the circumstances existing at the time of the prior order with those existing at the time of the modification hearing. Because this determination depends heavily upon the evidence presented, appellate courts ordinarily defer to the trial judge's resolution of disputed factual issues unless the court has abused its discretion.

Modification Requires More Than a Simple Income Change
Many parents believe that any increase or decrease in salary automatically results in a new child support amount. Texas law is considerably more nuanced.

The trial court must first determine whether a statutory basis for modification exists under Section 156.401. If that threshold requirement has been satisfied, the court must then determine the obligor's current net resources under Chapter 154, apply the statutory guidelines or determine whether a deviation is appropriate, and ultimately decide whether the requested modification is in the child's best interest.

For that reason, successful modification cases often require careful analysis of compensation beyond a parent's base salary. Bonuses, commissions, self-employment income, business ownership interests, deferred compensation, restricted stock awards, rental income, retirement benefits, and other sources of income may all become relevant depending upon the facts of the particular case. Likewise, allegations of intentional unemployment or underemployment frequently require the court to determine whether earning capacity, rather than actual earnings, should be considered in calculating child support.

Modification of child support therefore involves considerably more than recalculating percentages. It requires the trial court to apply the statutory framework established by Chapters 154 and 156 of the Texas Family Code while exercising its equitable discretion to reach a result that serves the best interests of the child.