Rule 1910.16-4.Support Guidelines. Calculation of Support Obligation. Formula.
Adopted September 6, 1989 · Last amended August 11, 2025 · Last verified June 30, 2026
Full Text of Rule 1910.16-4
Plain-English Summary
This rule does the arithmetic of support. Using the schedule amount, its formula allocates the basic child support between the parents in proportion to their incomes, with adjustments for the time the child spends with each parent and for any spousal support or alimony pendente lite. The result is the obligor's guideline support amount.
Frequently Asked Questions
How is each parent's share of support calculated?
By the Rule 1910.16-4 formula, which divides the schedule amount between the parents in proportion to income, with adjustments for custody time and spousal support.
Official Note
Comment. : Section 11051 of the Tax Cuts and Jobs Act of 2017, Pub.L. No. 115-97, amended the Internal Revenue Code by repealing the alimony deduction—the amount of spousal support, alimony pendente lite, and alimony paid or received—from the payor’s gross income and the alimony inclusion into the payee’s gross income. Subdivision (a)(1) governs an order entered on or after January 1, 2019, or for a modification of an order entered before January 1, 2019, that includes spousal support or alimony pendente lite in which the Act expressly applies to the modification. Subdivision (a)(2) governs a modification of an order entered before January 1, 2019 that includes spousal support or alimony pendente lite in which the Act does not apply to the modification. Subdivision (c) Example 1. If the obligor and the obligee have monthly net incomes of $5,000 and $2,300, respectively, the basic child support obligation is $1,960 for two children. Using the income shares formula in Part I, the obligor’s basic child support obligation is 68%, or $1,333. If the children spend 40% of the annual overnights with the obligor, the formula in Part D or Part II applies to reduce the obligor’s basic child support obligation to 58%, or $1,137. If the children spend 45% of the annual overnights with the obligor, the obligor’s basic child support obligation is reduced to 53%, or $1,039. If the children spend an equal number of the annual overnights with the obligor and obligee, the obligor’s basic child support obligation is reduced to 48%, or $941. Subdivision (c) Example 2. Mother and Father have monthly net incomes of $3,000 and $2,700, respectively. Mother has filed for support for the parties’ two children with whom the parties share time equally. As the parties have equal custody and Mother has the higher monthly net income, Mother cannot be the obligee. Although Mother initiated the support action, she would be the obligor. Pursuant to the Basic Child Support Schedule in Pa.R.Civ.P. 1910.16-3, the basic child support obligation for two children at the parties’ combined monthly net income is $1,715 per month. Mother’s share is 53%, or $909. Application of the Part II or Part D formula results in a 20% reduction in support when the obligor has 50% custody of the children. Mother’s adjusted percentage share of the basic support obligation is 33% (53% ⫺ 20% = 33%) and the preliminary adjusted basic child support obligation is $566 (33% of $1,715). However, as this amount would result in Father having a greater share of the parties’ combined monthly net income ($3,266 vs. $2,434), Mother’s basic child support obligation would be adjusted to $150 per month to allocate the parties’ combined monthly net income equally between the two parties and would be the presumptive basic child support obligation payable to Father under these circumstances. Subdivision (c) Example 3. If the obligor and the obligee have monthly net incomes of $3,000 and $2,500, respectively, the basic child support obligation for two children is $1,694. The obligor’s share is 55%, or $932 ($1,694 × 55%). If the children spend equal time with the parties, the formula in Part II or Part D results in a basic child support obligation of $593 ($1,694 × 35%) payable to the obligee. Since this amount results in the obligee having monthly net income of $3,093 and the obligor having monthly net income of $2,407, the obligor’s basic child support obligation would be adjusted to $250 to equalize the combined monthly net income between the parties and would be the presumptive basic child support obligation payable to the obligee under these circumstances. Subdivision (d)(1) Example 1: If the parties have three children, one child resides with Mother and two children reside with Father, and the parties’ monthly net incomes are $4,000 and $2,000 respectively, Mother’s basic child support obligation is calculated using the schedule in Pa.R.Civ.P. 1910.16-3 for two children at the parties’ combined monthly net income of $6,000. The basic child support obligation is $1,774. As Mother’s income is 67% of the parties’ combined monthly net income, Mother’s basic child support obligation for the two children living with Father is $1,189. Father’s basic child support obligation is calculated using the schedule in Pa.R.Civ.P. 1910.16-3 for one child at the parties’ combined monthly net income of $6,000. The basic child support obligation is $1,186. Father’s basic child support obligation for the child living with Mother is $392. Subtracting $392 from $1,189 produces a basic child support obligation of $797 payable to Father as child support. Subdivision (d)(1) Example 2: If the parties have two children, one child resides with Mother and the parties equally share custody (50% ⫺ 50%) of the other child, and the parties’ monthly net incomes are as set forth in Subdivision (d)(1) Example 1. The basic child support obligation is calculated using the schedule in Pa.R.Civ.P. 1910.16-3 for the one child primarily residing with Mother at the parties’ combined monthly net income of $6,000, the basic child support obligation is $1,186. Father’s income is 33% of the parties’ combined monthly net income, and the basic child support obligation for the child living with Mother is $392. For Mother’s obligation for the child with the equally shared custody arrangement, using the schedule in Pa.R.Civ.P. 1910.16-3 for one child at the parties’ combined monthly net income of $6,000, the basic child support obligation is $1,186. Mother’s proportionate share of the combined monthly net incomes is 67%, but it is reduced to 47% after applying the shared parenting time adjustment for 50% custody under subdivision (c). Mother’s basic child support obligation for the shared custody child is $557 ($1,186 × 47%). As Mother’s obligation is greater than Father’s obligation, Father is the obligee and receives the net of the two obligations by subtracting $392 from $557, or $165. Subdivision (d)(2) Example 1: The parties have two children, and one child spends 50% of the annual overnights with Mother, who has the higher monthly net income, and the other child spends 20% of the annual overnights with Mother. Add those percentages together and divide by the number of children (50% plus 20% = 70% divided by 2 children = 35% average time with Mother). Pursuant to subdivision (d)(2)(ii)(B), Mother is not entitled to a reduction in the support order for substantial parenting time. Subdivision (d)(2) Example 2: The parties have three children. Two children spend 50% of the annual overnights with Mother, who has the higher monthly net income, and the third child spends 30% of the annual overnights with Mother. Add the percentages of custodial time for all three children together and divide by the number of children (50% plus 50% plus 30% = 130% divided by three children = 43.33% average percentage of time with Mother). Pursuant to subdivision (d)(2)(ii)(B), Mother is entitled to a reduction in the support order for substantial parenting time. Subdivision (d)(2) Example 3: The parties have three children, Mother has primary custody (60% ⫺ 40%) of one child, Father has primary custody (60% ⫺ 40%) of one child, and the parties share custody (50% ⫺ 50%) of the third child. The parties’ monthly net incomes are $2,500 (Mother) and $2,000 (Father). As a result of the custodial arrangement, Father owes support for the child in the primary custody of Mother and Mother owes support for the child in the primary custody of Father and for the child shared equally between the parties. Father’s basic child support obligation is calculated using the schedule in Pa.R.Civ.P. 1910.16-3 for one child at the parties’ combined monthly net income of $4,500. The basic child support obligation is $1,011. Father’s proportionate share of the combined monthly net incomes is 44% but is reduced to 34% after applying the shared parenting time adjustment for 40% custody under subdivision (c). Father’s basic child support obligation for this child is $344 ($1,011 × 34%). Mother’s basic child support obligation is calculated using the schedule in Pa.R.Civ.P. 1910.16-3 for two children at the parties’ combined monthly net income of $4,500. The basic child support obligation is $1,527. Mother has varying partial or shared custody of the two children (40% and 50%). Under subdivision (d)(2), the custodial time is averaged or in this case 45%. Mother’s proportionate share of the combined monthly net incomes is 56%, but it is reduced to 41% after applying the shared parenting time adjustment for 45% custody under subdivision (c). Mother’s basic child support obligation for these children is $626 ($1,527 × 41%). Offsetting the support obligations consistent with subdivision (d)(1), Mother’s obligation is greater than Father’s obligation, and Father is the obligee receiving the net of the two obligations by subtracting $344 from $626, or $282. In cases with more than one child and varied partial or shared custodial schedules, it is not appropriate to perform a separate calculation for each child and offset support amounts as that method does not consider the incremental increases in support for more than one child built into the schedule of basic child support. Concerning subdivision (e), see Pa.R.Civ.P. 1910.19(h). Historical Commentary The following commentary is historical in nature and represents statements of the Committee at the time of rulemaking: Explanatory Comment—2005 Pa.R.C.P. No. 1910.16-4(a) sets forth the income shares formula used to establish the support obligation. Subdivision (b) provides the method for calculating support for seven or more children as the basic support schedule in Pa.R.C.P. No. 1910.16-3 sets forth the presumptive amount of support for up to six children. Subdivision (c) sets forth the method for calculating the presumptive amount of support in cases where the children spend 40% or more of their time during the year with the obligor. When there is equal time sharing, subdivision (2) reduces the support obligation further so that the obligor does not pay more than is necessary to equalize the parties’ combined monthly net income between the two households. Subdivision (3) expressly excludes SSR cases from the application of this rule. Since the SSR already reduces support to a minimal level, a further reduction should not be given for the amount of time spent with the children. Subdivision (d) relates to the calculation of support in divided or split custody cases. It retains the existing method for offsetting the parties’ respective support obligations when one or more of the children resides with each party. Subdivision (e) governs spousal support obligations when the custodial parent owes spousal support. It has not been amended, other than to update the example to be consistent with the new schedule at Pa.R.C.P. No. 1910.16-3. Explanatory Comment—2010 The basic support schedule incorporates an assumption that the children spend 30% of the time with the obligor and that the obligor makes direct expenditures on their behalf during that time. Variable expenditures, such as food and entertainment, that fluctuate based upon parenting time were adjusted in the schedule to build in the assumption of 30% parenting time. Upward deviation should be considered in cases in which the obligor has little or no contact with the children. However, an upward deviation may not be appropriate if an obligor has infrequent overnight contact with the child, but provides meals and entertainment during daytime contact. Fluctuating expenditures should be considered rather than the extent of overnight time. A downward deviation may be appropriate when the obligor incurs substantial fluctuating expenditures during parenting time but has infrequent overnights with the children. The calculation in Pa.R.C.P. No. 1910.16-4(c) reduces an obligor’s support obligation further if the obligor spends significantly more time with the children. The obligor will receive an additional 10% reduction in the amount of support owed at 40% parenting time, increasing incrementally to a 20% reduction at 50% parenting time. This method still may result in a support obligation even if custody of the children is equally shared. In those cases, the rule provides for a maximum obligation so that the obligee does not receive a larger portion of the parties’ combined monthly net income than the obligor.
Amendment History
The provisions of this Rule 1910.16-4 adopted September 6, 1989, effective September 30, 1989, 19 Pa.B. 4151; amended January 27, 1993, effective immediately, 23 Pa.B. 701; amended December 7, 1998, effective April 1, 1999, 28 Pa.B. 6162; corrected February 5, 1999, effective April 1, 1999, 29 Pa.B. 645; amended March 2, 2000, effective immediately, 30 Pa.B. 1646; amended October 27, 2000, effective immediately, 30 Pa.B. 5837; amended June 5, 2001, effective immediately, 31 Pa.B. 3306; amended October 30, 2001, effective immediately, 31 Pa.B. 6273; amended September 24, 2002, effective immediately, 32 Pa.B. 5044; amended November 9, 2004, effective immediately, 34 Pa.B. 6315; amended May 17, 2005, effective immediately, 35 Pa.B. 3216 and 3900; amended September 27, 2005, effective 4 months from the date of this order, 35 Pa.B. 5643; amended January 12, 2010, effective May 12, 2010, 40 Pa.B. 586; amended July 8, 2010, effective September 6, 2010, 40 Pa.B. 4140; amended August 3, 2011, effective in 30 days, 41 Pa.B. 4531; amended August 26, 2011, effective September 30, 2011, 41 Pa.B. 4849, 4851; amended August 3, 2011, effective in 30 days, 41 Pa.B. 6766; amended January 31, 2012, effective February 28, 2012, 42 Pa.B. 930; amended April 9, 2013, effective August 9, 2013, 43 Pa.B. 2272; amended July 2, 2014, effective in 30 days on August 1, 2014, 44 Pa.B. 4476; amended September 25, 2014, effective in 30 days on October 25, 2014, 44 Pa.B. 6553; amended April 29, 2015, effective July 1, 2015, 45 Pa.B. 2352; amended October 14, 2016, effective January 1, 2017, 46 Pa.B. 6817; amended February 10, 2017, effective May 1, 2017, 47 Pa.B. 1123; amended February 9, 2018, effective April 1, 2018, 48 Pa.B. 1093; amended July 30, 2018, effective January 1, 2019, 48 Pa.B. 4960; amended December 28, 2018, effective January 1, 2019, 49 Pa.B. 170; amended August 17, 2021, effective January 1, 2022, 51 Pa.B. 5539; amended August 11, 2025, effective January 1, 2026, 55 Pa.B. 5978. Immediately preceding text appears at serial pages (407095) to (407110).