The Texas Family Code generally requires that child support would change by 20% or $100.00 per month to constitute a material change of circumstance AND it has been three years since the last order regarding child support. Texas Family Code section 156.401. However, if a person ordered to pay child support were to lose a job, that would be a material and substantial change in circumstances that would presumably support a child support change. See the same statute above. Another such change would be the move of the child’s residence from one conservator to another.