Yes, there is a minimum amount of child support that can be ordered which for 2 children is 25% of his net resources using the minimum wage pay scale. The minimum wage rate is $6.55 per hour and it will be based on a 40-hour work week. (Minimum wage will increase to $7.25 effective July 24, 2009). At minimum wage, this equals an annual salary of $13,624. Thus, at 25%, his monthly child support amount would be approximately $230 per month.
However, this is only used if he can prove he does not have a job. If he has a job, he will pay 25% of his net resources as long as his pay does not go under the minimum wage rate. If it does, then the minimum wage rate will prevail. This is found in section 154.068 of the Texas Family Code. Net resources is calculated by taking his gross pay and subtracting federal taxes, social security, and Medicare. If he pays for the children's health insurance or pays union dues, that will also lower his net resources.
§ 154.068. WAGE AND SALARY PRESUMPTION. In the absence of evidence of the wage and salary income of a party, the court shall presume that the party has wages or salary equal to the federal minimum wage for a 40-hour week.
Please note, 25% for two children is only if there are no other children he is responsible for. If he has other children that are either his biological or adopted children under the age of 18, then the percentage can change.
Keep in mind that a judge can look at his prior income and if the judge determines the reduction in pay is intentional, then a reduction of child support may not occur. He will have to prove to the court that his change in pay is unavoidable.