This memorandum opinion was not selected for pub lication in the New Mexico Appellate Reports. Please see Rule 12-405 NMRA for restrictions on the citation of unpublished memorandum opinions. Please also note that this electronic memorandum opinion may contain computer-generated errors or other deviations fr om the official paper version filed by the Court of Appeals and does not include the filing date. IN THE COURT OF APPEALS OF THE STATE OF NEW MEXICO 1
KATHERINE BALLARD, 2 Petitioner-Appellant, 3

v. NO. 33,617 4 TUXIE BALLARD, 5 Respondent-Appellee, 6 and 7 STATE OF NEW MEXICO ex rel. HUMAN SERVICES DEPARTMENT, 8 CHILD SUPPORT ENFORCEMENT DIVISION, 9 Intervenor-Appellee. 10 APPEAL FROM THE DISTRICT COURT OF UNION COUNTY 11 John M. Paternoster, District Judge 12 Kalm Law Firm, P.C. 13 Cory J. Kalm 14 Thomas L. Kalm 15 Albuquerque, NM 16 for Appellant 17 Tuxie Ballard 18 Paradise, TX 192 Pro Se Appellee 1 Larry Heyeck, Deputy Director of Legal Services 2 Santa Fe, NM 3 Hector H. Balderas, Attorney General 4 Lila Bird, Special Assistant Attorney General 5 Santa Fe, NM 6 for Intervenor-Appellee 7 MEMORANDUM OPINION 8 HANISEE, Judge. 9
{1} Petitioner Katherine Ballard appeals the district court’s denial of her request for 10 an upward adjustment of Respondent Tuxie Ballard’s child support obligation. 11 Petitioner argues the district court erroneous ly used Schedule B of the child support 12 guidelines set out in NMSA 1978, Sec tion 40-4-11.1(K) (2008) to determine 13 Respondent’s current support obligation. Petiti oner also appeals the district court’s 14 failure to include income from Respondent ’s “side jobs” inits calculation of 15 Respondent’s child support obligation and its order granting Intervenor-Appellee State 16 of New Mexico Human Services Department, Child Support Enforcement Division 17 (HSD)’s motion to intervene. We affirm. 18
{2} Petitioner obtained a default judgmen t against Respondent on March 28, 2011. 19 In addition to dissolving their marriage, the default judgment awarded joint legal 203 custody of their two children (Children) to both Petitioner and Respondent, but gave 1 Petitioner primary physical custody. The default judgment set out a fairly detailed 2 schedule dividing periods of responsib ility for Children over the year between 3 Petitioner and Respondent. It calculated Res pondent’s child support obligation using 4 Worksheet A of Section 40-4-11.1(K). U nder the default judgment, Respondent was 5 obliged to provide Children with health insurance and to pay Petitioner child support 6 in the amount of $771.12 per month. 7
{3} On December 19, 2012, HSD filed a motion to intervene and a separate motion 8 to modify downward the amount of ch ild support payable by Respondent. Petitioner 9 opposed HSD’s motion to modify, arguing instead that the default judgment should 10 be modified to increase Respondent’s childsupport obligation. The district court 11 granted HSD’s motion to intervene and de signated a special master to conduct a 12 hearing on HSD’s motion to modify. 13
{4} After the hearing, the special master recommended denying both HSD’s motion 14 to decrease and Petitioner’s motion to increase Respondent’s child support obligation. 15 The special master found that no downward modification of support was warranted 16 because: (1) there was no dem onstration that the timeshari ng order was being strictly 17 adhered to by Respondent, such that it woul d be proper to lower the amount paid to 18 Petitioner; (2) Respondent would not qualify for a presumption of changed 194 circumstances if income from his “side jobs” was consider ed; and (3) the established 1 monthly support obligation fit a timesharing circumstance somewhere between 2 Worksheets A and B. Becausethe increase in support would not exceed twenty 3 percent of the current support obligati on, no upward modification was recommended 4 by the special master. Petitioner filed objections to the special master’s 5 recommendation, which the district court overruled. Petitioner appeals the district 6 court’s orders granting HSD’s motion to intervene and denying Petitioner’s request 7 that the default judgment be modifi ed to increase Respondent’s child support 8 obligation. 9
{5} In rejecting the competing claims for modification of Respondent’s child 10 support obligation, and as part of its app lication of the child support guidelines set 11 forth separately in Section 40-4-11.1, the district court calculated the amount of time 12 that Children spent with Respondent under the default judgment’s custody 13 arrangement. The district court concluded th at the default judgment set out a “shared 14 responsibility” custody arrangement, and therefore that Worksheet B (and not 15 Worksheet A, which the default judgment had used) must be used to determine 16 Respondent’s current support obligation. The district court then determined 17 Petitioner’s and Respondent’s monthly income s, expenditures on health insurance and 18 work-related childcare, and other facts rele vant to a calculation of income under the 195 guidelines. It too concluded that Respondent ’s current guidelines obligation did not 1 exceed his obligation under the default judgment by more than twenty percent, so 2 NMSA 1978, Section 40-4-11.4 (1991), Subs ection (A)’s presumption of changed 3 circumstances did not apply. Consequently, no change to Respondent’s child support 4 obligation was effectuated. 5
{6} Petitioner’s first argument on appeal is that the district court was precluded by 6 res judicata from reassessing the applicableworksheet because the default judgment 7 itself states that “Worksheet A is appr opriately utilized for calculating support.” We 8 do not agree. To be sure, New Mexico courts have sometimes used the doctrine of res 9 judicata to reject efforts to relitigate i ssues decided by a divorce decree. But New 10 Mexico courts have used res judicata inthis context only when a party seeks to 11 relitigate factual disputes that were decided in a previous decree, not factual disputes 12 concerning changes subsequent to the entry of th e most recent decree. See, e.g. , Fox 13 v. Doak , 1968-NMSC-031, ¶ 12, 78 N.M. 743, 438 P.2d 153 (holding that a 14 modification of child custody order was precluded by res judicata when the underlying 15 finding of changed circumstances was based on facts in existence prior to entry of 16 previous order). 17
{7} Here, Petitioner argues that it was improper for the district court to recalculate 18 the custody arrangement set out in the default judgment in order to determine whether 196 Respondent’s support obligation had increas ed by more than twenty percent after 1 entry of the default judgment. But as we have noted above, the cases that have applied 2 res judicata in the context of child cu stody and support have only done so when a 3 party argues changed circumst ances based on facts in existence prior to the entry of 4 the most recent decree. Extending res j udicata to preclude litigation of facts 5 subsequent to the most recent judgment would be contrary to the plain text of Section 6 40-4-11.4(A), which provides for modification of a child support obligation “upon a 7 showing of material and substantial changes in circumstances subsequent to the 8 adjudication of the pre-existing order .” (Emphasis added.) So we instead assess 9 whether the district court’s use of WorksheetB in its “application of the child support 10 guidelines” under Section 40-4-11.4(A) was supported by substantial evidence. See 11 Thompson v. Dehne , 2009-NMCA-120, ¶ 8, 147 N.M. 283, 220 P.3d 1132 (“The 12 setting of child support is left to the sound di scretion of the [district] court as long as 13 that discretion is exercised in accordance with the child support guidelines [and we] 14 review the [district] court’s findings of fact to determine if there is substantial 15 evidence to support the determinations.” ) (internal quotation marks and citations 16 omitted). We conclude that it was. 17
{8} NMSA 1978, Section 40-4-1 (1973) allows either party to a marriage to petition 18 a district court to dissolve the marriage. Whenthe district court enters a final judgment 197 dissolving the marriage, it “may make such an order for the . . . maintenance . . . of the 1 [parties’] minor children . . . as may seem just and proper.” NMSA 1978, § 40-4- 2 7(B)(4) (1997). As stated, maintenance of the parties’ minor children is determined 3 by reference to the child support guidelines in Section 40-4-11.1. See § 40-4-11.1(A) 4 (“In any action to establish or modify childsupport, the child support guidelines as set 5 forth in this section shall be applied to determine the child support due and shall be 6 a rebuttable presumption for the amount of such child support.”); see also Leeder v. 7 Leeder , 1994-NMCA-105, ¶ 6, 118 N.M. 603, 884 P.2d 494 (stating that a court may 8 deviate from the guidelines calculation of child support “only when the children’s 9 needs for care, maintenance, and education, in light of the parents’ financial resources, 10 justify a departure”). 11
{9} “The basic child support obligation shall be calculated based on the combined 12 income of both parents and shall be paid by them proportionately pursuant to 13 Subsection K of [Section 40-4-11.1].” Sec tion 40-4-11.1(E). Subsection K of Section 14 40-4-11.1 provides a “basic child support schedule” that fixes each parent’s child 15 support obligation based on the parents’ combined income and the number of children 16 they have. This number is then “adjus ted” upward or downward using the physical 17 custody arrangement set out in the court’s most recent child custody adjudication. 18 Section 40-4-11.1(F). 198 {10} The physical custody adjustment is madeusing one of two worksheets set out 1 in Subsection K: Worksheet A or Work sheet B. The appli cable worksheet is 2 determined by the type of custody arrangeme nt in effect: if the custody arrangement 3 has the children spending less than thirty-fivepercent of the time with one parent, then 4 Worksheet A applies; if both parents havethe children for more than thirty-five 5 percent of the time, Worksheet B applies. Section 40-4-11.1(D), (F); see also Erickson 6 v. Erickson , 1999-NMCA-056, ¶ 3, 127 N.M. 140, 978 P.2d 347. 7
{11} The district court may modify an existing child support obligation when a 8 parent demonstrates “material and substantial changes in circumstances subsequent 9 to the adjudication of the pre-existing or der.” Section 40-4-11.4(A). Although Section 10 40-4-11.4 does not specifically define “material and substantial changes in 11 circumstances[,]” it does provide for a presumption of material and substantial 12 changes in circumstances when “application of the child support guidelines in Section 13 40-4-11.1 . . . would result in a deviation upward or downward of more than twenty 14 percent of the existing child support obligation and the petition for modification is 15 filed more than one year after the fili ng of the pre-existing order.” Section 40-4- 16 11.4(A). 17
{12} To reiterate, Petitioner contends that b ecause the default judgment expressly 18 states that Worksheet A applies to de termine Respondent’s child support obligation, 199 the district court erred by using Work sheet B to determine Respondent’s current 1 support obligation and whether Section 40-4-11.4’s presumption of changed 2 circumstances applies. But the presumpti on of changed circumstances is determined 3 by “application of the child support guidelines in Section 40-4-11.1[,]” not application 4 of the Worksheet set out in the divorce decree. Section 40-4-11.4(A). As we have 5 explained, applying the guidelines requires the district court to make a physical 6 custody adjustment, and making the physical custody adjustment requires the district 7 court to determine each parent’s periods of responsibility under the existing custody 8 order. See NMSA 1978, § 40-4-9.1(F) (1999) (“When joint custody is awarded, the 9 court shall approve a parenti ng plan for the implementation of the prospective custody 10 arrangement prior to the award of joint cu stody. The parenting plan shall include a 11 division of a child’s time and care into periods of responsibility for each parent.”) 12 That is what the district court did in this case, and the fact that the analysis employed 13 by the district court followed a motion to modify a default judgment is of no moment 14 to the district court’s application of the applicable statutes. 15 We conclude that the district court did not err in applying the child support guidelines 16 using Worksheet B. 17
{13} Petitioner next argues that the districtcourt should have included Respondent’s 18 $400 monthly income from “side jobs” in its determination of whether a presumption 1910 of changed circumstances justified an upward modification of Respondent’s support 1 obligation. But as Petitioner acknowledges, the only way that the inclusion of this 2 income in a support calculation would re sult in a twenty percent increase in 3 Respondent’s support obligation would be if the district court used Worksheet A to 4 calculate Respondent’s support obligation. Having rejected Petitioner’s arguments on 5 this threshold issue, there is no basis to reverse on the second issue Petitioner raises. 6
{14} Lastly, Petitioner argues that HSD does not have statutory authority to intervene 7 and seek to modify the child support obligations of a non-custodial parent. But the 8 district court denied HSD’s motion to modify Respondent’s support obligation, and 9 HSD has not appealed that ruling. Accordi ngly, there is no basis to consider this 10 argument. See In re Estate of Heeter , 1992-NMCA-032, ¶ 23, 113 N.M. 691, 831 P.2d 11 990 (“On appeal, error will not be corrected if it will not change the result.”). 12 13
{15} The district court is affirmed. 14
{16} IT IS SO ORDERED. 15

_________________________________ 16 J. MILES HANISEE, Judge 17 WE CONCUR: 18

_________________________________ 19 MICHAEL D. BUSTAMANTE, Judge 2011 _________________________________ 1 LINDA M. VANZI, Judge 2