In Re the Marriage of: Mark N. Stageberg, petitioner, Appellant, vs. RoxAnne G. Stageberg Erickson, Respondent, Hennepin County Support and Collections, Respondent.

may not be cited except as provided by

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

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C8-97-2006

In Re the Marriage of:

Mark N. Stageberg, petitioner,

Appellant,

vs.

RoxAnne G. Stageberg Erickson,

Respondent,

Hennepin County Support and Collections,

Respondent.

 Filed May 5, 1998

 Affirmed

Crippen, Judge

Hennepin County District Court

File No. DC151753

Kathleen M. Picotte Newman, Larkin, Hoffman, Daly & Lindgren, Ltd., 1500 Norwest Financial Center, 7900 Xerxes Avenue South, Bloomington, MN 55431-1194 (for appellant)

RoxAnne G. Stageberg Erickson, 7011 Oak Pointe Curve, Bloomington, MN 55438 (pro se respondent)

Calvin Giles, Assistant Hennepin County Attorney, Hennepin County Government Center, 800 South Sixth Street, Minneapolis, MN 55487 (for respondent)

Considered and decided by Crippen, Presiding Judge, Lansing, Judge, and Peterson, Judge.

  U N P U B L I S H E D O P I N I O N

 CRIPPEN, Judge

Appellant Mark N. Stageberg contends that the trial court inappropriately approved a cost-of-living adjustment in his spousal maintenance obligation because (a) even though his average income since 1992 has substantially increased, he had no such increase in 1996, and (b) he incurred a significant debt load between 1994 and 1996. We affirm.

 FACTS

Appellant and respondent RoxAnne Erickson were married in 1967 and divorced in 1990. The dissolution order and decree included a provision that appellant pay permanent spousal maintenance to respondent in the amount of $3,500 per month. The determination of appellant's ability to pay maintenance was based on evidence that he had an annual income of about $190,000, based on earnings produced over several years through 1988. The trial court denied respondent's 1992 request for a cost-of-living adjustment to her maintenance award, finding that appellant had average yearly earnings of nearly $189,000 through 1988 but had reduced earnings in 1989 and 1991 so that he averaged earnings of only $172,000 for the years 1989-91.

In 1997, Hennepin County, on behalf of respondent, announced that appellant's maintenance obligation would be increased to cover cost-of-living increases over the past five years. In proceedings following appellant's exercise of his right to challenge the adjustment, the trial court permitted the five-year cost-of-living increase (14.25%, or $499 per month, effective June 1, 1997), finding that appellant's average earnings of $231,470 for the years 1992-96 were well above his earlier earnings.

 D E C I S I O N

  1. Standard of law; standard of review

The statute governing cost-of-living adjustments to maintenance awards specifies a three-step process. Minn. Stat. § 518.641 (1996). First, the obligee is entitled to a cost-of-living adjustment upon application and notice to the obligor at least 20 days prior to the effective date. Id., subds. 1, 2. Second, the obligor can object to the cost-of-living adjustment before it becomes effective, preventing the automatic increase. Id., subd. 2(c). Third, if the obligor objects, a trial court hearing will be held. After such a hearing, the district court "may" direct that part or all of the cost-of-living adjustment not take effect if the obligor demonstrates an insufficient income increase that prevents "fulfillment" of the adjusted obligation. Id., subd. 3.

The trial court has broad discretion in determining spousal maintenance awards. Rutten v. Rutten, 347 N.W.2d 47, 50 (Minn. 1984). The court has the same broad discretion in determining whether to permit a cost-of-living adjustment under section 518.641. McClenahan v. Warner, 461 N.W.2d 509, 511 (Minn. App. 1990). The trial court's underlying findings of fact must be affirmed unless they are clearly erroneous. Gessner v. Gessner, 487 N.W.2d 921, 923 (Minn. App. 1992).

  2. Income increase

The obligor has the burden of showing that a cost-of-living adjustment should be reduced or denied altogether. Minn. Stat. § 518.641, subd. 3; Blomgren v. Blomgren, 386 N.W.2d 378, 382 (Minn. App. 1986). Under the statute, appellant must show that he has experienced an "insufficient increase" that "prevents fulfillment" of the cost-of-living adjustment. Minn. Stat. § 518.641, subd. 3.

Because the trial court found that appellant's 1996 earnings were $154,849, appellant contends that the court erred when it acted on appellant's average earnings of $231,470 over five years. But there is nothing in the record to suggest that appellant's average earnings since 1992 are an inaccurate reflection of his usual income experience or that his 1996 earnings reflect any change in his likely production of income. See Veit v. Veit, 413 N.W.2d 601, 606 (Minn. App. 1987) (affirming determination of income by averaging the earnings of an obligor whose income fluctuates). The trial court's findings of fact on appellant's income increase are not clearly erroneous.

  3. Business indebtedness

Appellant asserts that the trial court erred by failing to reduce his income by the amount of his business debt. Appellant suggests that his average earnings of $231,470 over five years should be reduced by $55,282, one-fifth of his business indebtedness at the end of 1996.

The record includes no evidence suggesting that appellant's debt at the end of 1996 is directly chargeable to his production of income in specified years. Moreover, there is no evidence that this debt load is unique, that it must be immediately repaid, or that it cannot be liquidated without sacrificing appellant's production of income. Neither the trial court nor this court is permitted to speculate on any of these facts and the trial court did not clearly err in finding the amount of appellant's income increases. See generally, Tuthill v. Tuthill, 399 N.W.2d 230 (Minn. App. 1987) (holding that appellate court cannot speculate to fill gaps in appellant's proof of facts).

  Affirmed.