Code of Virginia § 20-108.2 provides a guideline for determination of child support; quadrennial review by Child Support Guidelines Review Panel; executive summary.

C. (4) G. 3. Shared custody support.

(d) Minimum standards. Any calculation under this subdivision shall not create or reduce a support obligation to an amount which seriously impairs the custodial parent's ability to maintain minimal adequate housing and provide other basic necessities for the child. If the gross income of either party is equal to or less than 150 percent of the federal poverty level promulgated by the U.S. Department of Health and Human Services from time to time, then the shared custody support calculated pursuant to this subsection shall not be the presumptively correct support and the court may consider whether the sole custody support or the shared custody support is more just and appropriate.