Attorney Jason A. Weis of Curran Moher Weis published a detailed step-by-step child support calculation guide on the Virginia Family Law Blog in September 2025. That guide, drawing directly from Virginia Code § 20-108.1 and § 20-108.2, walks through every component of the calculation with the practical clarity that parents navigating this process need.
Step One: Determine Each Parent's Gross Monthly Income
The calculation starts with gross income, meaning income before taxes and deductions. Virginia law defines income broadly to include wages, salaries, commissions, bonuses, dividends, interest, rental income, retirement benefits, and any other regular source of money. Self-employment income requires calculating gross receipts minus necessary business expenses to arrive at the net self-employment income that then factors into the support calculation.
Both parents' monthly gross incomes are calculated, then combined to produce a combined monthly income figure. This combined income is the input for the Virginia child support guidelines schedule. The schedule assigns a total child support obligation based on the combined income and the number of children.
Step Two: Apply the Guideline Schedule
Virginia Code § 20-108.2 contains the guideline schedule, which is a table listing combined income levels against the number of children to produce a basic child support obligation. That basic obligation represents the total amount both parents are expected to contribute to the child's basic needs. The obligation is then divided between the parents in proportion to each parent's share of combined income.
For example, if combined income is $8,000 monthly and one parent earns $5,000 while the other earns $3,000, the first parent contributes 62.5% of the obligation and the second contributes 37.5%. The parent with primary physical custody receives their proportional share from the other parent.
Step Three: Adjust for Additional Costs
The basic obligation is then adjusted upward for three key categories of additional costs. Work-related child care costs paid by either parent are added to the basic obligation and divided proportionally. Health insurance premium costs attributable to the child are similarly added and shared proportionally. Extraordinary medical expenses may also be addressed.
These adjustments can significantly change the final child support number. In Northern Virginia, where child care costs are substantial, work-related child care expenses often add a meaningful amount to the guideline calculation. Parents who pay for these costs get credit; those who don't don't.
Step Four: Apply Any Deviation Factors
After arriving at the adjusted guideline figure, either party may argue that the guideline amount is inappropriate based on the fifteen deviation factors in Virginia Code § 20-108.1. The court must then make written findings explaining why a deviation is warranted, what the guideline amount would have been, and what the deviation amount is.
In practice, most Virginia child support cases follow the guidelines fairly closely. Deviations do occur, particularly when one or both parents have unusually high income, when special needs of the child create costs beyond the standard schedule, or when the custody arrangement involves substantial shared time that affects the financial analysis.
For parents with questions about their specific child support calculation, attorney Weis's firm at (571) 328-5020 in Fairfax provides consultations tailored to Northern Virginia cases.
Conclusion
Virginia's child support calculation process is structured, systematic, and grounded in a clear statutory framework. While the guidelines produce a starting number that courts presume correct, the full analysis considers additional costs and potential deviations that can meaningfully change the final amount. Understanding each step of that process empowers parents to approach support discussions and court proceedings with informed, realistic expectations.