from the Superior Court in Maricopa County No. FC2012-000532
The Honorable Pamela Hearn Svoboda, Judge
Ellsworth Family Law P.C., Mesa By Glenn D. Halterman Counsel
and Brooke LLP, Phoenix By Travis M. Wheeler, Amanda E. Heitz
Counsel for Respondent/Appellee
Presiding Judge Samuel A. Thumma delivered the opinion of the
Court, in which Judge Randall M. Howe and Judge Patricia A.
Orozco  joined.
Justin Mitton (Father) appeals from the superior court's
post- decree order modifying child support. Because child
support was improperly calculated, the order is vacated and
the issue of child support is remanded for further
proceedings consistent with this opinion.
AND PROCEDURAL HISTORY
Candice Mitton (Mother) and Father divorced by consent decree
entered in 2013. The decree provided Mother and Father equal
parenting time with their children, with Father paying Mother
child support. Mother and Father currently have three minor
children: a daughter, who is 17, and twin boys, who are 10.
Father later filed a petition to modify child support, which
was addressed at an August 2015 evidentiary hearing. Mother
and Father testified that, with their consent, their daughter
was living with Mother full time, while the twins continued
to have equal time with each parent. Because their daughter
was living with Mother full time, Mother argued that Father
needed to pay more child support. The court took the matter
under advisement and directed counsel to file child support
worksheets setting forth their positions. Mother filed two
worksheets (one for their daughter living solely with Mother
and one for the twins reflecting equal parenting time with
Mother and Father). Father timely objected, arguing
Mother's worksheets overstated his child support
obligation, and filed competing worksheets, including a
combined worksheet for all three children. In a subsequent
ruling, the court set child support in an amount calculated
by adding together the two worksheets Mother had filed.
This court has jurisdiction over Father's timely appeal
from that ruling pursuant to Article 6, Section 9, of the
Arizona Constitution and Arizona Revised Statutes (A.R.S.)
sections 12-120.21(A)(1) and -2101(A)(1)
Father argues the superior court's method of combining
two separate child support worksheets "was not
consistent with the Guidelines and resulted in a support
award that far exceeded what is contemplated by the
Guidelines." This method, Father argues, resulted in a
"clearly disproportionate increase" in his child
support obligation. Father argues this method ignores that
the Guidelines account for "the fact that some of the
expenses associated with supporting a single child (such as
providing housing) do not increase in equal proportion to the
number of children in a family."
Mother counters that the superior court did not err, citing
an example in section 16 of the Guidelines, titled
"Multiple Children, Divided Custody, " that uses
separate worksheets and treats each child as an only child.
See A.R.S. § 25-320 Appendix § 16. The
example, however, assumes each parent has sole custody of at
least one child-which is not the case here-making section 16
How the Guidelines approach child support for unusual
parenting time arrangements is a matter of law subject to de
novo review. Hetherington v. Hetherington, 220 Ariz.
16, 21 ¶ 21 (App. 2008). The Guidelines are based on an
"income shares model" in determining child support.
Nash v. Nash,232 Ariz. 473, 476 ¶ 7 (App.
2013). The income shares model "is based on two
principles: (1) 'The total child support amount
approximates the amount that would have been spent on the
children if the parents and children were living together,
' and (2) 'Each ...