dissenting.
{¶ 22} I dissent because I would reverse the trial court’s decision to disregard the uncontested terms of the parties’ separation agreement and to calculate the father’s child support in a manner contrary to the desire of both parties. As part of their settlement agreement, the father and the mother agreed to calculate child support by using the worksheet for split parental rights. Neither party contested the use of that worksheet on direct appeal, nor did the mother challenge the calculation employed for determining child support during the Child Support Enforcement Agency’s (“CSEA”) administrative review. The mother’s only request to CSEA was that the father’s support obligation be modified to reflect the parties’ recent agreement that she would provide the children’s health insurance through her employer, because the father had been temporarily unemployed and, upon becoming reemployed elsewhere, was facing higher costs to insure the children through his new employer. To her credit, the mother also informed CSEA that aside from upcoming summer-camp expenses, there were no longer any childcare expenses for their youngest child, which arguably would have reduced the father’s support obligation. Instead of honoring the calculation agreed to by the parties and recalculating support using the worksheet for split parental rights based on the provisions of the parties’ separation agreement, the trial court calculated child support using the worksheet for shared parenting, which resulted in more thah a four-fold increase in the father’s support obligation.
{¶ 23} This court has previously stated that “[t]he parties’ separation agreement, incorporated as part of the divorce decree, is a contract between the parties. Therefore, the separation agreement is subject to the same rules of *364construction, which govern other contracts.” Ivanov v. Ivanov, 9th Dist. No. 24998, 2010-Ohio-1963, 2010 WL 1780142, at ¶ 19. Here, the parties’ separation agreement incorporates their shared-parenting plan, which calculated the father’s child-support obligation in accordance with the worksheet for split parental rights. Though the parties should have arguably employed the worksheet for shared parenting to calculate the father’s support obligation, they chose instead to use the worksheet for split parental rights, seemingly based on their desire to “split” their parenting time and responsibilities equally between one another. To the extent that the trial court erred in the first instance by permitting the parties to use a worksheet for split parental rights instead of ordering the parties to calculate support based on the worksheet for shared parental rights, that error is not properly before this court as the subject of this appeal.
{¶ 24} When a trial court has erroneously adopted the parties’ agreement with respect to child support, this court has noted that “[a]ny error in the trial court’s adoption of the agreed entry [calculating child support] has been waived [if] neither party timely appealed that order.” Smith v. Collins (1995), 107 Ohio App.3d 100, 104, 667 N.E.2d 1236 (noting that “[i]t [wa]s clear that the trial court failed to follow [the Supreme Court’s] mandate [relative to deviations from the child-support worksheets] in adopting the parties’ agreed journal entry,” but concluding that “[because] neither party timely appealed the agreed entry, that entry must be accepted as the existing child support order of the court”). See also Jindra v. Jindra, 9th Dist. No. 04CA0011-M, 2004-Ohio-6742, 2004 WL 2895789, at ¶ 6 (declining to address the trial court’s failure to adhere to the child-support statute in the parties’ original separation agreement when neither party had appealed from that judgment).
{¶ 25} More recently, the Eleventh District considered similar circumstances when the trial court had “no doubt * * * erred in its original decree of dissolution” by failing to fully complete a child-support worksheet or document factors to support a significant deviation in husband’s child-support obligation as agreed to under the terms of the parties’ separation agreement. In re Marriage of Henson, 11th Dist. No. 2006-T-0065, 2007-Ohio-4376, 2007 WL 2410356, at ¶ 24, 29-33. When the trial court later granted husband’s motion to modify his support obligation, the Eleventh District reversed, concluding:
Although flawed and erroneous, the original decree of dissolution is not void ab initio, as [the father] contends, but rather, merely voidable. Thus, as a voidable judgment, the original order may not be collaterally attacked, but instead may be addressed only on direct appeal. Since it was not, this erroneous order must be taken as presumably correct.
*365Since the original decree is merely voidable and because [the father] did not directly appeal that order, which adopted the separation agreement that he voluntarily entered into, any error in the order cannot now be cured via a motion to modify. * * i,: [W]e cannot now revisit the past on a motion to modify * * * by curing the trial court’s initial failure to follow [statutory] requirements * * *. The trial court’s initial error is quite simply not properly before the court.
Id.
{¶ 26} As noted, neither party appealed from the trial court’s order establishing the father’s support based on the use of a worksheet for split parental rights. Even if the parties were not precluded from raising this issue, this court cannot sua sponte address the propriety of the child-support worksheet used in this instance, when neither party has challenged its use. See Sahr v. Sahr, 5th Dist. No. 09 CA 3, 2009-Ohio-4055, 2009 WL 2469544, at ¶ 19, fn. 2. Moreover, I consider the situation here, when the parties agreed to use the worksheet for split parental rights, no different than when parties agree to a deviation from the calculated amount of support. Jindra, 2004-Ohio-6742, 2004 WL 2895789, at ¶ 8 (enforcing the parties’ agreement to apply a 29 percent downward deviation to the amount of support calculated by the child-support guidelines).
{¶ 27} For the foregoing reasons, I would reverse the trial court’s judgment because it abused its discretion in using the worksheet for shared parenting to calculate a modification to the father’s child-support obligation, in contradiction to the unambiguous agreement of the parties to calculate support using the worksheet for split parental rights. Therefore, I dissent.