To calculate child support in PA, you follow four steps: determine each parent’s monthly net income under the state’s rules, add those incomes together and look up the basic obligation on the Pennsylvania Basic Child Support Schedule for your number of children, assign each parent a share of that obligation equal to their percentage of the combined income, and then adjust the obligor’s share for custody time and shared expenses like health insurance and childcare. Pennsylvania uses the Income Shares Model, which estimates what parents would have spent on their children if the household had stayed together and splits that amount by income.1Unified Judicial System of Pennsylvania. Pennsylvania Rules of Civil Procedure 1910.16-1 – Amount of Support, Support Guidelines The math is formulaic, but small errors in income figures or overnight counts can shift the final number by hundreds of dollars a month.
Step 1: Find Each Parent’s Monthly Net Income
Start with monthly gross income from every source. Rule 1910.16-2 counts wages, salaries, bonuses, commissions, self-employment earnings, business profits, interest, rent, royalties, dividends, Social Security benefits, disability payments, workers’ compensation, and unemployment compensation.2Pennsylvania Code. 231 Pa Code Rule 1910.16-2 – Support Guidelines, Calculation of Monthly Net Income
Income is ordinarily averaged over at least six months. That matters for anyone with uneven pay. A construction worker who earns heavily in summer and little in winter will be assessed on a blended figure, not whatever last month’s paycheck looked like.
From gross income, subtract only the deductions the rule allows:
- Federal, state, and local income taxes. Pennsylvania’s flat state rate is 3.07%, and local earned income taxes vary by municipality.3Department of Revenue. Tax Rates
- FICA (Social Security and Medicare), plus self-employment tax for independent earners.
- Unemployment compensation taxes and Local Services Taxes.
- Mandatory union dues.
- Non-voluntary retirement contributions. Only employer-mandated pension deductions qualify.
- Alimony paid to the other party.
That list is exhaustive. Voluntary 401(k) contributions, life insurance premiums, loan payments, and similar expenses do not reduce your income for support purposes.2Pennsylvania Code. 231 Pa Code Rule 1910.16-2 – Support Guidelines, Calculation of Monthly Net Income
If a Parent Isn’t Working or Is Underemployed
When a parent is unemployed or working below their ability, the court will impute income equal to what that parent could realistically earn. The court weighs employment history, job skills, education, age, health, criminal record, local job market conditions, and whether the parent has made genuine efforts to find work. Imputed income cannot exceed what the parent could earn from a single full-time job, and the court has to account for any childcare costs the parent would incur by working. The reasoning behind an earning-capacity finding must be stated in writing or on the record.4Pennsylvania Code and Bulletin. 231 Pa Code Rule 1910.16-2 – Support Guidelines, Calculation of Monthly Net Income
Step 2: Look Up the Basic Obligation on the Schedule
Add both parents’ net incomes to get a combined monthly net income. Take that total and the number of children into the Basic Child Support Schedule under Rule 1910.16-3. The schedule is a large table that returns a single dollar amount: the total monthly obligation for both parents combined.5Pennsylvania Code. 231 Pa Code Rule 1910.16-3 – Support Guidelines, Basic Child Support Schedule
The schedule covers combined monthly net incomes up to $30,000. The figures are drawn from economic research into what intact families at each income level typically spend on their children, and they are updated periodically. The current schedule is published in the Pennsylvania Code, and there is an online estimator through the Pennsylvania Child Support Program.
Step 3: Split the Obligation by Income Share
The schedule amount is not divided evenly. Each parent carries a share equal to their percentage of the combined net income. If one parent nets $4,800 a month and the other nets $3,200, the combined total is $8,000. The higher earner’s share is 60%; the lower earner’s is 40%.6Pennsylvania Code and Bulletin. Pennsylvania Code 231 Rule 1910.16-1 – Support Obligation, Support Guidelines
Only the non-custodial parent (the obligor) writes a check. The custodial parent’s share is presumed to be spent directly on the child through housing, food, and daily expenses.
Step 4: Apply the Shared Custody Adjustment
If the obligor has the children for 40% or more of annual overnights (146 or more nights a year), a rebuttable presumption kicks in that the support amount should be reduced. A parent who has the kids nearly half the time is already spending on their food, housing, utilities, and activities during that time.7Pennsylvania Code. 231 Pa Code Rule 1910.16-4 – Support Guidelines, Calculation of Support Obligation, Formula
The formula takes the obligor’s percentage of overnights, subtracts 30%, and reduces the obligor’s income-share percentage by that difference. An obligor with 50% custody (about 183 nights) sees a 20-point reduction (50 minus 30) applied to their normal percentage share. The reduction grows as overnights grow. Even in a true 50/50 arrangement, the higher-earning parent usually still pays something; the adjustment lowers the number but rarely zeroes it out unless both parents earn nearly the same amount.
Add-Ons on Top of the Basic Amount
The schedule covers ordinary costs like food, clothing, shelter, and transportation. Health insurance, childcare, and large out-of-pocket medical bills are handled separately under Rule 1910.16-6, using the same income-share percentages from Step 3.8Pennsylvania Code. 231 Pa Code Rule 1910.16-6 – Support Guidelines, Basic Support Obligation Adjustments, Additional Expenses Allocation
Health insurance. The premium cost attributable to the child’s coverage is divided proportionally. If one parent has access to affordable employer coverage, that parent is typically ordered to carry the child.
Childcare. Reasonable childcare costs that let a parent work or attend school for income are allocated between the parents. Whoever pays the daycare bill up front receives a credit for the other parent’s proportional share in the final order.
Unreimbursed medical expenses. Annual unreimbursed medical costs above $250 per person are split by income percentage. Costs under that threshold are absorbed by whichever parent pays them. The $250 is prorated for any order covering less than a full year.9Pennsylvania Code. 231 Pa Code Rule 1910.16-6 – Support Guidelines, Basic Support Obligation Adjustments, Additional Expenses Allocation
The Floor and the Ceiling
Self-Support Reserve
Pennsylvania protects low-income obligors. If paying the full guideline amount would drop the obligor’s remaining income below a minimum, the obligation is reduced. For 2026, the self-support reserve is $1,255 per month. A court will not enter an order that leaves the paying parent with less than this amount after support, unless the custodial parent’s income is even lower.
When Combined Income Exceeds $30,000 a Month
Above $30,000 in combined monthly net income, the schedule no longer applies and Rule 1910.16-3.1 provides a formula. The base is the obligation at $30,000, plus a percentage of every dollar above that line, which varies by number of children:10Legal Information Institute. 231 Pa Code r 1910.16-3.1 – Support Guidelines, High-Income Cases
- One child: $3,608 plus 4.0% of combined net income above $30,000
- Two children: $4,250 plus 4.0%
- Three children: $4,951 plus 4.7%
- Four children: $5,530 plus 5.3%
- Five children: $6,083 plus 5.8%
- Six children: $6,613 plus 6.3%
The obligation can never fall below what it would have been at $30,000 combined. The court can then adjust the preliminary number up or down based on the child’s reasonable needs, the deviation factors in Rule 1910.16-5, and the parents’ expense statements, with a written explanation of the final award.
When a Court Can Deviate from the Guideline Number
The schedule amount is presumptively correct, but Rule 1910.16-5 lets a court go higher or lower based on nine factors:
- Unusual needs or unusual fixed obligations
- A parent’s other support obligations
- Other household income
- The child’s age
- The parents’ relative assets and debts
- Medical expenses not covered by insurance
- The standard of living of the parents and the child
- The duration of the marriage (in spousal support cases only)
- Other relevant factors, including the child’s best interest
Any deviation has to be documented: the guideline amount, the reason for departing from it, the facts supporting the departure, and the final adjusted amount. Undocumented deviations are vulnerable on appeal.11Pennsylvania Code. 231 Pa Code Rule 1910.16-5 – Support Guidelines, Deviation
Split Custody Is Calculated Differently
Split custody is not the same as shared custody. It applies when each parent has primary custody of at least one child. The court calculates a separate obligation for each parent, based on the number of children living with the other, then offsets the two. The parent with the larger obligation pays the net difference.
In a three-child family where one child lives with the father and two live with the mother, the court first calculates what the father owes for the two children with the mother, then what the mother owes for the one child with the father. The smaller amount is subtracted from the larger, and only that net difference changes hands.12Unified Judicial System of Pennsylvania. Rule 1910.16-4 – Support Guidelines, Calculation of Support Obligation, Formula
One Thing the Guideline Does Not Cover
Pennsylvania does not require parents to pay for college through the support system. College costs can only be enforced if both parents voluntarily agreed to share them in a written agreement or court order. If you are expecting the guideline calculation to produce a tuition contribution, it won’t.