In Re the Marriage of : Norman George Yunis, petitioner, Appellant, vs. Susan Caroline Yunis, Respondent.

may not be cited except as provided by

Minn. Stat. § 480 A. 08, subd. 3 (1998).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C4-99-340

In Re the Marriage of :

Norman George Yunis, petitioner,

Appellant,

vs.

Susan Caroline Yunis,

Respondent.

 Filed August 31, 1999

 Affirmed

 Amundson, Judge

St. Louis County District Court

File No. F9-61-600794

Jane Binder, Christine Howard, 510 Marquette Avenue South, Suite 700, Minneapolis, MN 55402 (for appellant)

Cheryl M. Price, Melanie S. Ford, Hanft & Fride, 1000 U.S. Bank Place, 130 West Superior Street, Duluth, MN 55802 (for respondent)

Considered and decided by Halbrooks, Presiding Judge, Schumacher, Judge, and Amundson, Judge.

 U N P U B L I S H E D O P I N I O N

 AMUNDSON, Judge

The district court denied appellant's motion to terminate his spousal maintenance obligation. Appellant challenges the district court's decision arguing that respondent's income has substantially increased, thereby eliminating her need for spousal maintenance. We affirm.

 FACTS

The parties' marriage was dissolved by entry of a stipulated judgment on June 12, 1992. Pursuant to this agreement, appellant Norman Yunis was required to pay spousal maintenance in the amount of $600 per month to respondent Susan Yunis until she remarried, either party died, or until further court order. With cost of living increases, the amount of appellant's spousal maintenance obligation is currently $712 per month.

Appellant's gross income has remained largely unchanged since judgment was entered and is approximately $154,000 per year. The district court was provided with no information from which to derive any findings about appellant's monthly expenses.

Respondent's gross annual income has increased from approximately $29,600 to $58,900 per year due to an increase in employment income and receipt of investment income. Respondent's investment income is generated by a substantial inheritance she received and which the district court valued at $360,545. Income on this asset was calculated by the district court utilizing a six percent rate of return resulting in investment income of $21,600 per year. Accordingly, the district court found that respondent has a net monthly income of $4,689 ($1,800 employment income, $1,200 investment income, and $1,689 child support income).

The budget that respondent submitted to the district court totaled her monthly expenses at $5,509 per month. The district court reduced this budget to $5,000 per month, noting that the budget submitted by the respondent was "unfairly high" because she had included in her expenses $1,000 for a home equity line of credit without showing that this was the amount that she was required to pay each month and indicating the term of the loan. The district court found that adding the maintenance award amount of $475 ($712 less taxes) to respondent's net monthly income yielded an amount of $5,164 per month and determined that this amount was sufficient to meet her budget.

 D E C I S I O N

This court reviews a district court's determination of modification of spousal maintenance for abuse of discretion. Stich v. Stich, 435 N.W.2d 52, 53 (Minn. 1989). This court will not find an abuse of discretion unless the district court's determination is based on clearly erroneous conclusions, which are against logic and the facts on record. Rutten v. Rutten, 347 N.W.2d 47, 50 (Minn. 1984). The district court's findings of fact with regard to maintenance are also upheld unless "clearly erroneous." Gessner v. Gessner, 487 N.W.2d 921, 923 (Minn. App. 1992).

Modification of a maintenance order is governed by Minn. Stat. § 518.64, subd. 2(a) (1998), which provides in pertinent part as follows:

The terms of an order respecting maintenance or support may be modified upon a showing of one or more of the following: (1) substantially increased or decreased earnings of a party; (2) substantially increased or decreased need of a party * * *; (3) receipt of assistance * * *; (4) a change in the cost of living for either party * * *, any of which makes the terms unreasonable and unfair * * * .

Application of the statute requires a two-step analysis. The party seeking modification of a maintenance award must demonstrate that there has been a substantial change in circumstances and that this change has rendered the original maintenance award unreasonable and unfair. Hecker v. Hecker, 568 N.W.2d 705, 709 (Minn. 1997).

 I.

Appellant contends that the district court erred in calculating both the respondent's income and her expenses. At the time the district court heard appellant's motion to terminate spousal maintenance, appellant was in the process of transferring $23,925 to respondent. This amount constituted her share of the cash value in an investment account they owned while married. Appellant argues that the district court should have included interest income on the value of this asset in its calculation of respondent's income. The district court did not abuse its discretion when it chose not to include this amount in its calculation of respondent's investment income because appellant first requested its inclusion at the motion hearing and presented no evidence to the court that respondent had actually received this money.

Appellant next contends that the district court abused its discretion in calculating respondent's income when it applied a six percent rate of return on respondent's investments. Appellant merely asserts that at least a seven percent rate of return would have been more appropriate because a six percent rate of return is a return one gets by placing monies in a savings account and other investment vehicles earning higher returns are available to respondent. However, appellant cites no authority and provided no evidence to support his contention. See Tuthill v. Tuthill, 399 N.W.2d 230, 232 (Minn. App. 1987) (stating party "cannot complain" when their own failure to produce documentation leads, at least in part, to denial of their motion to modify maintenance). Indeed, the only evidence before the district court regarding interest rates was that provided by respondent demonstrating that her actual rate of return was less than six percent. On this record, the district court's utilization of the six percent rate of return will not be reversed.

Appellant argues that the district court incorrectly calculated respondent's income when it used her actual tax withholding status (single with zero exemptions) rather than one available to her according to the tax tables (head-of-household with three exemptions). To support its contention, appellant cites Minn. Stat. § 518.551, subd. 5 (1998), which governs support payments and recommends that tax tables be used when calculating an obligor's net income for the purpose of deriving an amount for child support.

Appellant further argues that it would have been more efficient for the district court to have calculated respondent's income using the tax tables instead of her actual tax withholding status because such a method would alleviate the need for repeated court appearances.[1] However this court's review is for abuse of discretion, not efficiency and it would be erroneous for this court to conclude that a district court abuses its discretion when it utilizes the actual tax withholding status of a party in calculating her net income. See Dinwiddie v. Dinwiddie, 379 N.W.2d 227, 229 (Minn. App. 1985) ("Net income is properly calculated based upon monies available to the taxpayer."). The district court's utilization of respondent's actual tax withholding status in calculating her income does not amount to an abuse of discretion.

Appellant alleges the district court also erred in its calculation of respondent's expenses when it and failed to reduce respondent's budget by the entire amount of the home equity line of credit and allowed the inclusion of a $537 per month expense for the parties' adult son. Appellant contends that the district court should have reduced respondent's budget by $1,000, the entire amount of her home equity loan payment, because respondent failed to indicate how much she was actually required to pay each month and failed to provide information regarding the term of the loan. That the district court considered the failure of respondent to provide some information regarding her home equity loan is evidenced by its reduction of this expense by approximately fifty percent. Because the district court's discounting of this expense is functionally a credibility determination, the district court was properly within the parameters of its discretion in its determination of the amount to allocate to this expense in respondent's monthly budget. See Sefkow v. Sefkow, 427 N.W.2d 203, 210 (Minn. 1988) (appellate courts defer to district courts credibility determinations).

Respondent's expenses should not have included the $537 per month expense for the payment of the parties' adult son's room and board expenses at college and therefore, her budget must be adjusted for voluntary expenses she assumes on behalf of the parties' adult child. See Musielewicz v. Musielewicz, 400 N.W.2d 100, 103 (Minn. App. 1987) (obligor spouse claimed expenses for the educational needs of the parties' adult children and court held that maintenance award may not consider needs of adult children), review denied (Minn. Mar. 25, 1987). While we find that the district court erred when it did not exclude the $537 expense from respondent's budget, we need not reach a determination on whether there has been a substantial change in circumstances because we find that appellant has failed to demonstrate that the original maintenance award is now unreasonable or unfair.

 II.

Appellant argues that because respondent's income has increased and because her income is now sufficient to meet her needs, the original maintenance award is unreasonable and unfair. A substantial increase in respondent's income, absent a showing that such an increase makes the original award of maintenance unreasonable and unfair, does not by itself constitute sufficient grounds to change the stipulated agreement as to spousal maintenance contained in the divorce decree. See Cisek v. Cisek, 409 N.W.2d 233, 236 (Minn. App. 1987), review denied (Minn. Sept. 18, 1987). The fact that the parties stipulated to the maintenance amount persuades us to affirm the district court's decision to keep the original maintenance award intact. When courts consider a modification of maintenance, the parties' stipulation carries great weight. Cisek, 409 N.W.2d at 236-37; Claybaugh v. Claybaugh, 312 N.W.2d 447, 449 (Minn. 1981) (district court should only reluctantly alter terms of stipulation governing maintenance).

The purpose behind an award of spousal maintenance is instructive.

[R]ecipients of permanent maintenance, once the decision has been made to award permanent rather than temporary maintenance, are not automatically penalized by loss of their permanent maintenance if, following a dissolution in which they were employed at the time, their earnings increase through the years. Permanent maintenance is compensatory in nature.

 Bochert v. Borchert, 391 N.W.2d 74, 76 (Minn. App. 1986). Here, while the decree failed to explicitly label the maintenance award as permanent, it functionally made the award permanent by requiring that it should continue until the respondent remarried, either party died, or further court order. Cf. Gales v. Gales, 553 N.W.2d 416, 418 (Minn. 1996) (stating that where district court failed to designate when maintenance payments would end, "the court, in effect, awarded permanent maintenance"). While respondent currently has income in excess of her monthly expenses, this amount is not excessive, nor has she demonstrated years of self-sufficiency, and appellant makes no assertion that he is unable to pay the award. The compensatory policy behind the maintenance award is not served by termination at this time.

Given that the parties stipulated to the amount of appellant's maintenance obligation and appellant has failed to demonstrate why continuation of his maintenance obligation is unreasonable and unfair in light of the changes in respondent's income and expenses, we affirm.

Pursuant to Minn. R. Civ. App. P. 139.06 and Minn. Stat. § 518.14, subd. 1 (1998) respondent's motion for an award of attorney fees in the amount of $5,793.80 is granted.

  Affirmed.

[1] Appellant suggests he will have to return to court to have respondent's income recalculated because respondent is over-withholding and will receive a tax refund next year, which is considered income.