Petitioner seeks further review of the court of appeals opinion affirming the district court’s order dividing the petitioner’s *646 pension using the service-factor-percentage method. We are asked to determine: (1) whether the court of appeals erred in finding the dissolution decree was not final until the qualified domestic relations order (“QDRO”) was entered and (2) whether the district court judge erred by adopting a QDRO that is alleged to be contrary to the specific language contained in the parties’ decree of dissolution. We find the court of appeals erred in determining the dissolution decree was not final until the QDRO was entered; however, its adoption of a QDRO employing the service-factor-percentage method was not contrary to the language of the dissolution decree and will be upheld.
I. Background Facts and Proceedings.
David Brown and Pamela Brown were divorced on June 30, 1999. At the time of the dissolution, David worked for the City of Sioux City as a manager in the Inspection Services Department. Through his employment, David has an IPERS pension plan. The dissolution decree approximated the value of David’s plan at $22,500.00 and awarded David sixty percent of the plan and Pamela forty percent of the plan. It then instructed the parties to submit a QDRO to the court for its approval.
A proposed QDRO was not submitted until March 2007 when both Pamela and David filed applications for entry of a QDRO. David filed a resistance to Pamela’s proposed QDRO. He claimed Pamela’s proposed QDRO uses the service-factor-percentage method to calculate her portion and incorrectly awards her forty percent of the gross monthly or lump sum benefit at the date of distribution. David also stated he had prepared a proposed QDRO in 2004, which was approved by IPERS. This QDRO directs IPERS to pay Pamela $9,000 or forty percent of the total amount in David’s IPERS account on the day of dissolution plus any accumulated interest on that amount.
After holding a hearing on the matter, the district court issued an order finding that
In re Marriage of Benson,
David subsequently filed a motion to amend, enlarge and clarify the district court’s orders adopting Pamela’s proposed QDRO and granting Pamela’s rule 1.904(2) motion. In this motion David requested the court hold a hearing to determine: (1) whether the court should sign a QDRO that applies the service-factor-percentage method and (2) whether the approved QDRO should provide for interest on both the preretirement benefits and postretirement death benefits and prohibit David from taking a lump-sum distribution. Pamela filed a resistance to David’s motion asserting that the service-factor-percentage method was appropriate. The court overruled David’s motion.
David appealed the district court’s ruling adopting Pamela’s proposed QDRO. This appeal was transferred to the court of appeals. The court of appeals affirmed *647 the district court’s order dividing David’s pension according to the service-factor-percentage method. David filed an application for further review.
II. Standard of Review.
We review dissolution cases de novo.
In re Marriage, of Sullins,
III. Discussion and Analysis.
In this case, we are asked two questions: (1) whether the court of appeals erred in finding the dissolution decree was not final until the QDRO was entered and (2) whether the district court judge erred by adopting a QDRO that is contrary to the specific language contained in the parties’ decree of dissolution.
A. Finality of Dissolution Decree.
In upholding the district court’s QDRO utilizing the service-factor-percentage method, the court of appeals found the parties’ decree unresolved at the time the district court received the parties’ proposed QDROs in 2007 because QDROs were never submitted to the decretal court for approval in 1999. Despite not having been raised by either party, the court of appeals found the entire decree was not final, including the division of the pension, and was still subject to change in this appeal. Unlike in
Sullins
and
Benson,
the leading cases in this area of law, this is not a direct appeal of the dissolution decree. Neither of the parties appealed the court’s division of their marital property in 1999. It is well established that the divorce decree was therefore final and settled all rights and interests of the parties in the property of one another.
Carr v. Carr,
According to Iowa Code section 598.21(7), property divisions made in a divorce decree are not subject to modification. Iowa Code § 598.21(7) (2007) (“Property divisions made under this chapter are not subject to modification.”). The dissolution court’s property division can only be challenged on direct appeal,
In re Marriage of Johnson,
This principle is not entirely true as applied to pension divisions. Because of certain anti-alienation restrictions in the Employee Retirement Income Security Act (ERISA) and the federal tax code, a QDRO must be filed for every pension
*648
division undertaken pursuant to a divorce.
See generally Rohrbeck v. Rohrbeck,
[W]e believe the issuance of a QDRO following a final decree for dissolution of marriage does not constitute an unlawful modification of property awarded under the original decree.
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ERISA does not require a QDRO to be part of the actual judgment in a case. It does, however, define several requirements which must be met before an order will be considered to be a QDRO.
In re Marriage of Bruns,
In
Rohrbeck,
the Maryland Court of Appeals further explained how a QDRO affects the finality of a divorce decree.
Rohrbeck,
To be final and conclusive ... [a] ruling must necessarily be unqualified and complete, except as to something that would be regarded as collateral to the proceeding. It must leave nothing more to be done in order to effectuate the court’s disposition of the matter. In the first instance, that becomes a question of the court’s intention: did the court intend its ruling to be the final, conclusive, ultimate disposition of the matter?
Id. at 774. Ultimately, the Rohrbeck court decided the district court had made it clear that the ruling it entered would not be final and complete until the QDROs were submitted and signed. Id. The court further explained that the QDROs submitted to the district court in that case were not merely perfunctory in nature, but were intended to resolve significant disagreements between the parties, such as whether the ex-spouse would receive survivor benefits. Id. at 775 n. 6.
The Rohrbeck court recognized that there may be situations in which a QDRO is intended to be collateral to the judgment.
[Wjhere a QDRO is needed to enforce an earlier entered support order, it obviously cannot be part of the underlying judgment. Even when the QDRO is required to effectuate a disposition ... there may be circumstances where the need for the order may not be apparent at the time the judgment is entered or where an order entered as part of a judgment has to be modified later because some deficiency in it precludes it from being accepted as a QDRO. We therefore expressly recognize the ability of a party otherwise entitled to a QDRO to obtain one as an aid to enforcing a previously entered judgment.
Id. at 774.
The Browns’ divorce decree states “A separate Qualified Domestic Relations Order should be entered in such regard. The parties should submit such an order to the Court for its signature.” Based upon the language of the dissolution court’s decree and the overall property division, we determine this QDRO is supplemental and not a part of the underlying decree.
*649
This finding is in line with our previous cases concerning supplemental orders to enforce property divisions. In
Welp,
we held that a supplemental order intended to enforce the court’s earlier dissolution decree dividing the parties’ property did not render the marriage dissolution unresolved.
In re Marriage of Welp,
The Browns’ divorce decree was final when entered. Any appeal to change the language of the district court’s division of the pension plan was required to be filed in 1999, not 2008. 1
B. Pension Plans. Pension plans are divisible marital property.
Sul-lins,
Under a defined-benefit plan, the future benefit received is determined in advance based on a benefit formula. Id. Such a plan “provides a benefit that is related to the employee’s earnings and length of service.” Id. at 254-55 (citing Steven R. Brown, An Interdisciplinary Analysis of the Division of Pension Benefits in Divorce and Post-Judgment Partition Actions: Cures for the Inequities in Berry v. Berry, 39 Baylor L. Rev. 1131, 1141-42 (1987)).
There are two acceptable methods for dividing pension benefits: the present-value method and the percentage method.
Sullins,
Although both methods may be used to divide a defined-benefit plan, we have expressed a preference for the percentage method.
Sullins,
As previously noted, David’s pension is a defined-benefit plan with its attendant problems in accurately determining its present value. Therefore, it was preferable that the percentage method be used to divide the benefits.
C. The QDRO. David contends the district court erred by adopting a QDRO that is contrary to the language of the parties’ decree of dissolution. He claims the language of the parties’ 1999 dissolution decree employed the present-value method. The problem is no one appealed the decree in 1999. We are now at the QDRO stage and must determine the effect of the language in the decree. After reviewing both parties’ proposed QDROs, the district court applied the percentage method to divide David’s pension, and therefore, adopted Pamela’s proposed QDRO.
A dissolution decree is construed like any other written instrument.
In re Marriage of Lawson,
“The decree should be construed in accordance with its evident intention. Indeed the determinative factor is the intention of the court as gathered from all parts of the decree. Effect is to be given to that which is clearly implied as well as to that which is expressed. Of course, in determining this intent, we take the decree by its four corners and try to ascertain from it the intent as disclosed by the various provisions of the decree.”
In re Marriage of Goodman,
David’s pension plan is divided in the dissolution decree as follows:
David has an IPERS pension plan which is currently valued at approximately $22,500.00. This plan should be divided so that David receives 60% of it and Pamela receives 40% of it. This is to account [for] the disparity in value of the property previously awarded the parties. A separate Qualified Domestic Relations Order should be entered in such regard. The parties should submit such an order to the Court for its signature.
(Emphasis added.)
David claims that according to this language, the estimated value of the pension on the date of dissolution was to be divided using the percentages provided by the court. He was to receive $13,500 and Pamela was to receive $9,000 of the pension plus ten percent interest on her portion compounded annually. He claims this would make her portion of the pension plan worth approximately $17,540 today. Pamela disputes this interpretation and as *651 serts that the percentage method was intended. 2
To determine whether the district court intended the division of David’s pension to be under the present-value method or the percentage method, we must interpret the language of the district court’s division. Although the decree purports to value the plan, the record does not contain any actuarial data submitted by either of the parties; thus, we can only conclude the district court based its figure on the statement that showed the value of David’s contributions to the plan up until the date of dissolution. This figure does not accurately value the present worth of the benefits.
See In re Marriage of Scheppele,
Absent detailed expert testimony involving mortality and discount rates, future contributions and other factors, an accurate present-value calculation was impossible.
Id.
at 248-^49. Thus, without such evidence, the percentage method would have been the only practical way to equitably divide David’s pension.
In re Marriage of Branstetter,
In interpreting divorce decrees, we give effect not only to that which is plainly expressed, but also that which is implied.
Goodman,
In its decree, the court also stated that its division of the pension was intended “to account [for] the disparity in value of the property previously awarded the parties.” In construing a dissolution decree, we give force and effect to every word if possible.
Lawson,
In trying to give a consistent, effective, and reasonable meaning to the language used, we find that the intent of the court’s language was to utilize the percentage *652 method to divide the pension. We therefore find Pamela’s proposed order comports with the intent of the original decree and affirm the district court’s order.
IV. Disposition.
We hold that the decree entered in 1999 was final as to the property division and the division of the pension plan. We further find that the district court properly utilized the percentage method to divide the pension plan. The order of the district court is affirmed.
DECISION OF COURT OF APPEALS VACATED; DISTRICT COURT JUDGMENT AFFIRMED.
Notes
. In January of 2004, David also filed a petition to modify the divorce decree to eliminate spousal support due to his remarriage, the death of the parties' youngest son, Pamela’s full-time employment, and Pamela’s long-term relationship with another individual. A trial was held on the matter. The district court overruled David’s petition. David appealed and the court of appeals affirmed the judgment of the district court.
. Pamela’s proposed QDRO states the service-factor formula should be used to determine the respondent’s benefits according to the following formula:
40% of the gross monthly or lump sum benefit payable at the date of distribution to the Member multiplied by the "service factor.” The numerator of the service factor is the number of quarters covered during the marriage period of October 7, 1972 through June 30, 1999 and the denominator is the Member's total quarters of service covered by IPERS and used in calculating the Member's benefit.
