Richard Alan Folden, Appellant, vs. State of Minnesota, Respondent.

may not be cited except as provided by

Minn. Stat. § 480 A. 08, subd. 3 (1996).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C5-98-31

Daniel Robert Nylen, petitioner,

Appellant,

vs.

Marna Jean Nylen,

Respondent.

 Filed May 19, 1998

 Affirmed in part, reversed in part, and remanded

 Schumacher, Judge

Hennepin County District Court

File No. DC207613

Daniel R. Nylen, 7940 Humboldt Avenue North, Brooklyn Park, MN 55444 (pro se appellant)

Marna J. (Nylen) Luer, 3645 Trenton Avenue North, Plymouth, MN 55441 (pro se respondent)

Considered and decided by Randall, Presiding Judge, Kalitowski, Judge, and Schumacher, Judge.

U N P U B L I S H E D O P I N I O N

 SCHUMACHER, Judge

Pro se appellant Daniel Robert Nylen (father) challenges the district court's order affirming a referee's child support determination. We affirm in part, reverse in part, and remand.

FACTS

The stipulated judgment dissolving the parties' marriage awarded respondent Marna Jean Nylen (mother) custody of the children and set father's support obligation. After one child moved in with father, father moved to modify custody and for support. In April 1997, a referee (a) allowed the child to stay with father; (b) noted the guideline support obligations for mother and father were $400 and $522 (respectively); (c) stated the support guidelines were "overbalanced" in favor of one child; (d) ordered father to pay mother $400 in monthly child support; and (e) continued the matter until July 1997. After a July hearing, the referee issued an order noting that the difference between the parties' guideline support obligations was $91.08, that the parties agreed custody of one child should be transferred to father, but did not alter father's $400 monthly support obligation. The district court affirmed. Father appeals.

D E C I S I O N

Child support may be modified if the moving party shows a substantial change in circumstances rendering the existing support award unreasonable and unfair. Minn. Stat. § 518.64, subd. 2(a) (1996). Whether to modify support is discretionary with the district court. Moylan v. Moylan, 384 N.W.2d 859, 864 (Minn. 1986). If custody is split between parents, it is proper to set each parent's obligation at the guideline amount and offset the obligations. Sefkow v. Sefkow, 427 N.W.2d 203, 216 (Minn. 1988).

Such an offset is an application of the child support guidelines. See Broas v. Broas, 472 N.W.2d 671, 673 (Minn. App. 1991) (noting, in joint physical custody cases, offsetting parties' guideline support obligations is an application of guidelines). Here, father notes his support obligation exceeds what he would pay if the district court offset the parties' guideline support obligations and claims the district court's findings are inadequate to support a deviation from the guidelines. Neither the district court nor the referee made the findings required for an above-guideline support obligation. See Minn. Stat. § 518.551, subd. 5(i) (1996) (if support deviates from guidelines, court "shall make" certain findings); see also Minn. Stat. § 645.44, subd. 16 (1996) ("`[s]hall' is mandatory"). Because the required findings are absent, a remand is proper. See Kahn v. Tronnier, 547 N.W.2d 425, 429 (Minn. App. 1996) (remanding above-guideline support obligation where required findings were absent), review denied (Minn. July 10, 1996).

Citing Bock v. Bock, 506 N.W.2d 321 (Minn. App. 1993), father claims the income of mother's husband is relevant to the support determination. Father is incorrect. See Minn. Stat. § 518.551, subd. 5(b)(1) (1996) ("net income" for support purposes excludes "income of the obligor's spouse"); Minn. Stat. § 518.551, subd. 5 (guideline support is function of obligor's income). Because this case involves split custody rather than the later-born children involved in Bock, father's cite to Bock to support his claim is misplaced; particularly in light of the offset used in Sefkow which, like this case, involved split custody.

The April order directed the parties to bring their most recent pay stubs to the July hearing. Apparently as a result of confusion about how non-paystub financial information would be presented at the July hearing, however, father's expenses were not presented to the referee. The district court refused to accept father's expense information because it had not been before the referee and father had not shown "good cause" for the district court to accept it. See Minn. R. Gen. R. Pract. 312.01 (on appeal to district court "[n]o additional evidence may be filed * * * except upon order of the court for good cause shown"). A failure to present evidence to a referee is not "good cause" requiring a district court to accept the evidence. See, generally, Taflin v. Taflin, 366 N.W.2d 315, 319 (Minn. App. 1985) (on appeal to this court, moving party "cannot complain" if his failure to provide information supporting his motion to modify support leads, at least in part, to motion's denial). Because it was unclear how non-paystub financial information was to be presented at the July hearing, we reverse the district court's refusal to accept father's financial information. On remand, the court shall accept and review that information.

Father claims support should be modified retroactively to a date prior to the date of his motion because mandatory mediation precluded him from moving to modify earlier than he did. See Minn. Stat. § 518.64, subd. 2(d) (Supp. 1997) (support modifications retroactive to date of motion unless moving party precluded from serving motion earlier). We disagree. See Buntje v. Buntje, 511 N.W.2d 479, 482 (Minn. App. 1994) (when mediation is involved, party seeking support modification may move to modify and seek a continuance of modification proceeding to allow mediation and thereby preserve a pre-mediation effective date for any modification).

Both parties make various references to the April 1997 order. Because that order is a temporary order, it is not appealable. Rigwald v. Rigwald, 423 N.W.2d 701, 705 (Minn. App. 1988). It is reviewable, however, to the extent it "affect[s]" the order from which the appeal is taken. Minn. R. Civ. App. P. 103.04. The April temporary order states that because "[g]uideline [c]hild support is over-balanced for one child," it would be inequitable to set mother's support obligation at the difference between the parties' guideline support obligations. This analysis, which is functionally a rejection of the support guidelines, seems to have been adopted in the district court's affirmance of the referee's September order when the district court stated that "it, in fact, would be wholly unfair to the two children in [mother's] custody to receive only the difference of the parties' respective obligations[.]" An analysis rejecting the guidelines is improper. See Martinco v. Hastings, 265 Minn. 490, 497, 122 N.W.2d 631, 638 (1963) ("[i]f there is to be a change in the statute, it must come from the legislature* * * ").

The district court found father waived any objection to the orthodontia expenses by not consulting with the orthodontist. The crux of father's opposition to paying the expenses is his claim that, contrary to mother's affidavit, the parties' agreed there would be no orthodontic treatment. Whether to believe mother or father regarding an agreement on orthodontic expenses is a credibility question. We defer to the district court's resolution of that question against father. See Sefkow, 427 N.W.2d at 210 (appellate courts defer to district court credibility determinations). We express no opinion on how to resolve the remanded issues.

  Affirmed in part, reversed in part, and remanded.