How a second family lowers Texas child support: the §154.128 and §154.129 methods, side by side

This post explains two computational methods the Texas Family Code provides for obligors supporting children in more than one household. It is not legal advice and it does not predict which method a court will use in your case. That choice belongs to the court, and the surrounding facts matter. Talk to a Texas family lawyer about your situation. What follows is the statute and the arithmetic.

If you are supporting children in another household, the guideline percentage that applies to your case is probably not the one in the headline table. Texas provides a separate mechanism for this, and most quick explainers skip it entirely because it requires either a chart lookup or a four-step computation rather than a single multiplication.

The mechanism matters. For an obligor with one child before the court and three children elsewhere, the applicable percentage drops from 20% to 14.75%. On $6,000 of monthly net resources that is a difference of $315 per month.

The short version

• The §154.125 percentages, 20% for one child and 25% for two, assume the obligor has no other children to support. If there are children in another household, a different calculation applies.
• Texas provides two lawful methods: the §154.129 chart, which is a direct percentage lookup, and the §154.128 four-step credit computation.
• Neither method is preferred by statute. §154.128 says the court “may” use the alternative method. The choice belongs to the court, and the two methods do not always produce the same number.
• The reduction is real but bounded. One child before the court with one other child moves the rate from 20% to 17.5%, not to half.
• “Children in another household” means children the obligor has a legal duty to support, not children they voluntarily help.

Why the standard percentages do not fit

The §154.125 table is the one everybody quotes: 20% of net resources for one child, 25% for two, 30% for three, rising to 40% at five or more. It is a clean rule and it is the right rule for a large share of cases.

It also contains an unstated assumption. Those percentages describe what a parent should contribute when the children before the court are the only children they are obligated to support. Once the obligor has a support duty toward children in another household, applying the headline percentage to the current case would over-allocate their resources, because the same net resources also have to reach the other children.

Texas addresses this in two adjacent sections that give the court a choice of method.

Method one: the §154.129 chart

The chart is a lookup. Two inputs go in, one percentage comes out. The rows are the number of children in another household, the columns are the number of children before the court, and the cell is the percentage of net resources.

Here is the top-left region, which covers the large majority of real cases:

Children in another household	1 child before court	2 children	3 children	4 children
0	20.00%	25.00%	30.00%	35.00%
1	17.50%	22.50%	27.38%	32.20%
2	16.00%	20.63%	25.20%	30.33%
3	14.75%	19.00%	24.00%	29.00%
4	13.60%	18.33%	23.14%	28.00%
5	13.33%	17.86%	22.50%	27.22%

The row for zero other children reproduces §154.125 exactly, which is the check that the chart is consistent with the base rule rather than a separate regime.

Three features of the table are worth noticing.

The first other child costs the most. Going from zero to one other child drops the one-child rate by 2.5 points, from 20% to 17.5%. Going from one to two drops it 1.5 points. From two to three, 1.25 points. The curve flattens, which is the intended shape: each additional obligation reduces the share available to the current case, but at a diminishing rate.

The reduction is proportionally smaller when more children are before the court. With four children before the court, one other child moves the rate from 35% to 32.2%, a reduction of about 8%. With one child before the court, the same other child produces a 12.5% reduction.

The percentages are not round. 27.38% and 32.20% look like the output of a formula rather than a negotiated table, because they are. The chart expresses a computed allocation, which is also why the four-step method can reach a different answer.

Method two: the §154.128 four-step credit

Section 154.128 provides an alternative that computes the credit rather than looking it up. In outline, the court determines the amount that would be ordered for all of the obligor’s children if they were in a single household, divides to establish a per-child share, applies that to the children before the court, and arrives at the guideline figure for the current case.

The reason the two methods diverge is that they distribute in different orders. The chart applies a percentage to the full net resources figure. The four-step method allocates a computed total across children. Where the cap is in play, or where the low-income schedule applies below $1,000 of monthly net resources, the ordering can move the result.

Our engine runs both methods and reports both figures with a note that Texas law permits either and that the court chooses. It does not pick a winner, because the statute does not, and presenting one number as the answer would misrepresent what the law provides. Where the two methods agree, the comparison line is suppressed automatically, since showing an identical number twice is noise rather than transparency.

A worked example

An obligor has monthly net resources of $6,000, one child before the court, and three children in another household whom they are legally obligated to support.

Without the multi-household adjustment, applying the headline §154.125 rate:

• 20% of $6,000 = $1,200 per month

With the §154.129 chart, reading the row for three other children and the column for one child before the court, the rate is 14.75%:

• 14.75% of $6,000 = $885 per month

The difference is $315 per month, or $3,780 per year. An estimate that ignores the other household overstates by more than a quarter.

Now change one input. Suppose there are two children before the court rather than one, with the same three children elsewhere. The chart gives 19.00%:

• 19.00% of $6,000 = $1,140 per month

Against the unadjusted 25% figure of $1,500, the adjustment saves $360 per month.

What counts as a child in another household

This is where the analysis usually goes wrong, and it goes wrong in both directions.

The test is legal duty to support, not household composition and not generosity. A child from a prior relationship for whom the obligor has a support order or a legal obligation counts. A biological child the obligor supports without any order generally counts, because the duty arises from parentage rather than from the order.

A stepchild the obligor is raising and supporting generally does not count, because absent adoption there is usually no legal duty of support. This one is genuinely counterintuitive, since the day-to-day financial reality of raising a stepchild is indistinguishable from raising a biological child. The statute keys on legal obligation.

Adult children generally do not count, because the duty of support ordinarily terminates under §154.001 at eighteen or on graduation from high school, whichever is later. A child with a disability supported under §154.302 is a different analysis.

Because the classification changes the percentage directly, it is worth getting right before relying on any number. This is also the input most likely to be misunderstood by a calculator that simply asks “how many other children do you have,” since that question does not distinguish a stepchild from a child subject to a support duty.

Where this interacts with the cap

The multi-household adjustment and the §154.125 cap are separate mechanisms and they apply in sequence. Net resources are capped first at the statutory ceiling, currently $11,700 per month, and the applicable percentage is then applied to the capped figure.

For a high earner with children in another household, both adjustments are live at once, and the order matters. Applying the percentage to uncapped resources and then capping produces a different and incorrect result. We covered the cap, including the fact that the OAG’s public calculator still applies the superseded $9,200 figure, in a separate post.

What to do with this

If you are supporting children in another household and your estimate used a flat 20% or 25%, the figure is too high. The correction is not an argument to make; it is a computation the statute provides for.

Two things are worth confirming before relying on any adjusted number. First, that the other children are ones you have a legal duty to support, under the test above. Second, which method produced the figure, since §154.128 and §154.129 can differ and a court may use either.

You can run both methods with our Texas child support calculator, which reports the §154.128 and §154.129 results side by side, cites the controlling section for each, and flags when they diverge rather than silently choosing one.

Primary sources

• Tex. Fam. Code Chapter 154 at statutes.capitol.texas.gov. §154.128 provides the alternative computation method, §154.129 contains the chart, §154.125 sets the base percentages and the cap, and §154.126 governs the above-cap analysis.
• §154.001 for the duration of the support duty, which determines whether a child in another household still counts.

Statutes reviewed 2026-07-30. Chart percentages reproduced from §154.129 as implemented and tested in our Texas engine.