This suit, brought by Betty Strecker, is based on allegations of sex discrimination and denial of equal pay against her employer, the Grand Forks County Social Service Board, its director in his official capacity and its individual members in their official *99capacity. The action was commenced under title VII of the Civil Rights Act of 1964, 42 U.S.C. § 2000e et seq., the Fair Labor Standards Act, as amended, 29 U.S.C. § 206(d), commonly known as the Equal Pay Act of 1963, and 42 U.S.C. § 1983. Mrs. Strecker began working for the Board in 1969 and since 1970 has held various positions relating to the administration of economic welfare to recipients in North Dakota. In 1977 she resigned her position to move to Bismarck, North Dakota with her husband where she assumed an administrative position with the state social services agency. Her basic claim relates to the fact that her successor, a male, David Braaten, was paid substantially more money than she received when employed by the Board. The district court, The Honorable Paul Benson, found that Mrs. Strecker had performed substantially equal work under similar working conditions but received less pay than her male successor. Nonetheless, the district court denied relief holding the Board had proven the disparity in pay was based on factors other than sex. She has appealed that ruling. We affirm the judgment of the district court.
Standard of Review.
Mrs. Strecker fails to demonstrate that any of the factual findings of the district court are clearly erroneous. She challenges the ultimate finding by the district court that she was not unlawfully discriminated against. Although there may be some confusion from our prior opinions, the ultimate conclusion of discrimination vel non is not governed by the clearly erroneous rule. See Shultz v. American Can Co.—Dixie Products, 424 F.2d 356, 360 n.6 (8th Cir. 1970). As the Fifth Circuit has observed:
Although discrimination vel non is essentially a question of fact it is, at the same time, the ultimate issue for resolution in this case, being expressly proscribed by 42 U.S.C.A. § 2000e-2(a). As such, a finding of discrimination or nondiscrimination is a finding of ultimate fact.... In reviewing the district court’s findings, therefore, we will proceed to make an independent determination of appellant’s allegations of discrimination, though bound by findings of subsidiary fact which are themselves not clearly erroneous. Also, ... we must determine whether there are requisite subsidiary facts to undergird the ultimate facts.
Causey v. Ford Motor Co., 516 F.2d 416, 421 (5th Cir. 1975) (citations omitted), quoted in Wade v. Mississippi Cooperative Extension Service, 528 F.2d 508, 516 (5th Cir. 1976).
Applying this standard of review, we proceed to the merits of Mrs. Strecker’s claim.
Equal Pay Act Violation.
Title VII and the Equal Pay Act must be construed in harmony. DiSalvo v. Chamber of Commerce of Greater Kansas City, 568 F.2d 593, 596 (8th Cir. 1978). Although plaintiff has brought suit under the Equal Pay Act as well as title VII, our basic analysis is essentially the same under either theory.1 To show a prima facie case, Mrs. *100Strecker must prove she performed substantially equal work as her successor but was paid less for it.
1. Prima Facie Case.
Contrary to defendants’ argument on appeal, we agree that plaintiff established a prima facie case. Plaintiff demonstrated that her wage rate, even during the last two years with the Board when she had assumed greater administrative responsibilities, was substantially less than that paid to her male successor. The record demonstrates she was performing work substantially equal to that performed by Braaten when he first assumed his duties. Under the statute, equal work means “jobs the performance of which requires equal skill, effort, and responsibility, and which are performed under similar working conditions.” 29 U.S.C. § 206(d). In determining whether work is equal, the court must look to the nature of the duties actually required and performed, not the official job description or title. Katz v. School District of Clayton, Missouri, 557 F.2d 153, 156 (8th Cir. 1977).
Although defendants attempt to urge that Braaten was hired as assistant director, the district court recognized the equality of work is not determined by duties or responsibilities which were to be assumed in the future. See Peltier v. City of Fargo, 533 F.2d 374, 377 (8th Cir. 1976). The evidence showed Mr. Braaten performed work substantially identical to Mrs. Strecker for nearly the first year he was employed by the Board. The district court correctly concluded that they performed equal work.
Once Mrs. Strecker has proven a prima facie case, defendants have the burden of proving that the disparity in pay was based on some factor other than sex. We conclude that they have done so. An analysis of the record unequivocally sustains this conclusion.
2. Statutory Defense.
Throughout her tenure with the agency, Mrs. Strecker’s classification and thus her salary were determined by the Central Personnel Division, Social Service Board of North Dakota (Central Personnel). The Grand Forks County Board could only recommend changes in classifications—Central Personnel had the final authority to determine classifications.
The structure of the classification system used by Central Personnel to evaluate positions and persons, and thus set salaries, is undisputed. Salaries are set by a dual classification system which classifies both positions and persons. Positions are classified by the responsibilities and duties they require. The qualifications or other characteristics of the person filling a position are irrelevant to the position’s classification. Persons are classified according to their experience in areas related to their job responsibilities and their education. Compensation systems that determine salaries on the basis of job duties and responsibilities, educational attainments and experience, which are related to the responsibilities and duties that employees must perform in their jobs, are clearly permissible under the Equal Pay Act. See Horner v. Mary Institute, 613 F.2d 706, 714 (8th Cir. 1980); EEOC v. Aetna Insurance Co., 616 F.2d 719, 726 & n.10 (4th Cir. 1980); EEOC v. New York Times Broadcasting Service, Inc., 542 F.2d 356, 359-60 (6th Cir. 1976); Herman v. Roosevelt Federal Savings & Loan Association, 432 F.Supp. 843, 851 (E.D.Mo.1977), aff’d, 569 F.2d 1033 (8th Cir. 1978) (the trial court said “It is clear that an employer may pay a higher starting salary to one who has education or experience relevant to the job to be performed. ... This Court does not wish to dictate to defendant what college courses it should consider as ‘job related’ and what monetary value it should give them.”); *101Brennan v. Federal National Mortgage Association, 12 FEP Cases 490 (C.D.Calif.1975). Salary differentials that result from applying these objective criteria do not violate that act.2
Under Central Personnel’s system, each classification is assigned a salary range. The job classification determines the minimum 3 and maximum salary which any person filling that position may receive. The personal classification determines the minimum and maximum salary which a person so classified may receive. Typically, a person’s classification matches the position classification so that the minimum and maximum salaries coincide. However, the system allows mismatching of personal and position classifications. If a job filled by an incumbent person is reevaluated to a higher classification, the system allows that person to remain in the job. This is called “under-filling” the position. In an underfilling situation, the person’s salary is determined by his or her personal classification—not the classification of the position. As the person gains the requisite experience or education, the person’s classification and salary are raised to equal the classification of his or her job.
On July 1, 1975, after some difficulty,4 Mrs. Strecker’s position was reclassified as an Administrative Officer I. Central Personnel also found that at that time Mrs. Strecker, personally, had the experience to be classified as an Administrative Officer I, thus, her personal classification matched her job’s classification.
Administrative Officer I classification required four years of college or four years of supervisory experience. Administrative Officer II classification required four years of college or equivalent experience and two years of professional experience within a public or private organization; Administrative Officer III required four years of college or equivalent and four years of professional experience.
On March 18, 1977, Strecker and Ohlsen submitted a request to reclassify Strecker’s position to an Administrative Officer III. This request was the result of prior discussions between Ohlsen and Ronald Leingang, State Social Service Board’s Personnel Officer.5 As a result of this reclassification request, Central Personnel reevaluated Strecker’s position to Administrative Officer III effective May 1, 1977.6 From May 1 to July 31, Strecker was underfilling her position. According to the undisputed evidence she was classified only as an Administrative Officer I before July 1, 1977, because she did not have the requisite experience even though her job was classified as an Administrative Officer III. Under the system, her salary remained that of an Administrative Officer I. Effective April 1, 1977, the Board increased her salary to the maximum within the Administrative Officer I range. The Board voted Strecker this retroactive increase on April 14, 1977, after it had received informal notice that her position was to be upgraded to Administrative Officer III, and prior to extending its *102offer to Braaten. At that time Central Personnel claimed Strecker was not qualified even for Administrative Officer II. On April 18th the Board urged Central Personnel to reconsider Mrs. Strecker’s appeal.7
Mrs. Strecker offered no evidence that in her ease the objective, neutral criteria of the Central Personnel classification system were not applied. Rather she argues that she was effectively prevented by Mr. Ohlsen from being evaluated under the non-biased classification system. She argues that Ohlsen prevented her from submitting her job description to Central Personnel for reevaluation and he did so because he was biased against women.
Although some evidence exists that occasionally Ohlsen demonstrated a sex-based bias, no evidence shows that this bias preeluded Strecker from having her job reclassified or that he was responsible for her staying at a lower salary. Ohlsen testified that although he had not initiated any written job reclassification requests for Strecker since 1975, he had, in 1975 and 1976, made oral inquiries and received oral assurances that plaintiff’s position did not warrant a higher classification. Defendants also introduced evidence that Ohlsen had supported reclassification requests in 1973 and 1975. The latter occurred when he supported plaintiff’s appeal of the classification of her job as Eligibility Technician III. The appeal was successful in raising the classification to Administrative Officer I.
Even if we assume that Ohlsen prevented Mrs. Strecker from seeking reclassification *103of her job and did so because she is a woman, and further assuming that her position would have been reclassified as Administrative Officer III before May 1,1977, the evidence is uncontradicted that she would not have received a higher salary because she did not have the personal qualifications to receive a salary at a level higher than Administrative Officer I prior to July 1, 1977. Under the system she could have underfilled this position but her salary would have been determined by her personal classification, Administrative Officer I. In this appeal, plaintiff does not dispute the fact that she did not meet the education or experience requirements of an Administrative Officer III at any time during her employ with the agency or the requirements of an Administrative Officer II prior to July 1,1977. Because plaintiff could not personally be classified above Administrative Officer I, any reclassification of her position would not have affected her salary.
The district court found that before 1977 plaintiff received the same percentage increase in salary as did all other employees of the agency and in 1977 her salary dramatically increased to the maximum allowed by her classification. Additionally, the court found that prior to the time she announced her intention to leave, the position of plaintiff’s salary within her classification was commensurate with the salary of the other two supervisors within their classifications. The court, in effect, held that the position of her salary within her classification was based upon factors other than her sex. The court was also persuaded by the fact that when the Board found out Mrs. Strecker was going to resign, they increased her salary to the maximum in her grade and attempted to have her classification upgraded so that she would be in a better bargaining position when she sought a new job in Bismarck.
The evidence further shows that every offer Ohlsen gave to prospects to replace Strecker was in the range allowed by the highest personal classification the prospect could attain with his or her education and experience. This is true for both male as well as female prospects.
We find the actions of Ohlsen and the Board were consistent in treating the agency’s supervisors equally within the confines of Central Personnel’s classification system. The evidence may well support the conclusion that the classification system underpaid capable people, as Mrs. Strecker was shown to be, however, there is no showing that the system was designed to, or in fact resulted in underpaying persons because of their sex. In any event, the bottom line is that Ohlsen and the Board could not advance Strecker without Central Personnel either altering its classification requirements or reevaluating Strecker’s personal qualifications. As the April 18th letter of the Board to the Central Personnel Division demonstrates, the Board supported Strecker in efforts to have her advanced. On the record it is difficult to understand what more Ohlsen or the Board could do to help Strecker. It is obvious that Central Personnel controlled her advancement, not Ohlsen or the Board.
In view of our holding affirming the district court, it is not necessary to pass on the issues raised by defendants on the cross appeal, No. 80-1063.8 Judgment affirmed.9
. There appears to be some difference in both substantive and procedural approach. Substantively, title VII requires a showing of discriminatory intent. The Equal Pay Act creates a type of strict liability; no intent to discriminate need be shown. Procedurally, once a plaintiff has shown a prima facie case of sex discrimination under title VII the burden of going forward with the evidence to articulate a nondiscriminatory reason shifts to the employer. Plaintiff still retains the ultimate burden of proof to show discriminatory intent and that the justification by the defendant was pretextual. See Furnco Const. Corp. v. Waters, 438 U.S. 567, 577-78, 98 S.Ct. 2943, 2949-50, 57 L.Ed.2d 957 (1978); McDonnell Douglas Corp. v. Green, 411 U.S. 792, 802-04, 93 S.Ct. 1817, 1824-25, 36 L.Ed.2d 668 (1973).
Under the Equal Pay Act, once a prima facie case has been established, 29 U.S.C. § 206(d) provides defendants four affirmative defenses. Defendants have the burden of proving the wage disparity is the result of:
(i) a seniority system; (ii) a merit system;
(iii) a system which measures earnings by quantity or quality of production; or (iv) a differential based on any other factor other than sex.
See Corning Glass Works v. Brennan, 417 U.S. 188, 196-97, 94 S.Ct. 2223, 2229, 41 L.Ed.2d 1 (1974); Shultz v. American Can Co.—Dixie Products, 424 F.2d 356, 362 n.10 (8th Cir. 1970). Title VII incorporates the Equal Pay *100Act defenses, 42 U.S.C. § 2000e-2(h), therefore, defendants who prove one of these defenses cannot be held liable under either the Equal Pay Act or title VII. See Gunther v. County of Washington, 602 F.2d 882, 891 (9th Cir. 1979); Molthan v. Temple Univ., 442 F.Supp. 448, 454 (E.D.Pa.1977).
. Arguably, the educational and experience requirements could be a pretext for sex discrimination, however, plaintiff introduced no evidence that this was Central Personnel’s intent when it established these criteria.
. If the position is “underfilled” the minimum does not apply.
. In 1975 reclassification came about because Central Personnel was at that time converting to the current system of classifications. Originally, Strecker’s position was classified as Eligibility Technician III. After appeal by Strecker with Ohlsen’s support, the position was reclassified to Administrative Officer I. Although Strecker’s testimony suggests she could not apply to Central Personnel for reclassification on her own, the evidence suggests to the contrary. Strecker’s petition for her 1975 reclassification was made on her own; Leingang, the State Personnel Director, indicated that an employee could petition on his or her own but that he would then notify the Board’s director.
. The evidence is not clear whether the decision to make this request occurred before or after plaintiff gave Ohlsen notice of her resignation.
. Mr. Longmire of Central Personnel indicated in an exhibit that the reclassification request supported reclassification to Administrative Officer III but only weakly. He also wrote that subsequent information he received indicating that the position would also serve as assistant director made the classification stronger.
. A letter, written by Frank Bowles, chairman of the Grand Forks County Social Service Board, to Richard Espeland, Director of the Central Personnel Division, strongly indicates that the Board fully supported Mrs. Strecker’s qualifications for the salary of an Administrative Officer III. After extolling Mrs. Strecker’s personal virtues and her professional competency the letter reads in part:
Now, it is my understanding that to be an Administrative Officer III, you must have a certain number of years of experience and a college degree, and that if you do not have the college degree, you substitute a year for a year’s experience. It is our contention here that this young lady in this agency has at least seven years experience as an administrator, and it is our contention further that the experience she had at First Federal Savings & Loan should be qualified. It is beyond the scope of our comprehension how a person who is so widely acclaimed in the State of North Dakota as an efficient, good administrator cannot qualify, for some vague reason, for the position.
To go further with this, we understand that when Central Calssification [sic] came in in [sic] 1974, she was “grandfathered” in, and that for some reason Central Classification feels that it’s not possible to add to the credentials by further experience after that time. Let me hasten to say to you, Mr. Espeland, that every month she stayed on the job we have seen her grow, and she has added to the job in maturity and in experience, and really, no matter what your regulations might say, the fact is she has become a better supervisor as time goes on. We believe in systems, too, and through systems we have some sort of order, but I think that you would agree with me that in any system that is set up, there are situations that develop that do not fit into the system.
We sincerely believe that Mrs. Strecker is an individual who, through her long years of association with this agency, deserves a compassionate hearing from your department, and that she be given her due. We really believe that she qualifies for Administrative Officer III, but if this exerts too much pressure on your department, we would settle for Administrative Officer II.
In closing, Mr. Espeland, we are talking about an individual who has proven herself and is a valued employee in the State of North Dakota. We don’t want this person to lose faith in the system, and we certainly could not afford her leaving the system because of discouragement with it. We have heard many fine things about your operation and know that you have problems in setting up a new department. We must not, however, allow the size of an operation to outweigh the situation of any one individual in the system. We, however, thank you for the time you spent in reviewing this and trust that you will give it your complete attention.
Thereafter on July 1, 1977, Central Personnel reclassified her to Administrative Officer II. It appears Central Personnel used July 1, 1975, the date she advanced to Administrative Officer I, as the date she completed her four years of supervisory experience as the equivalency for four years of college. On July 1, 1977, she had two additional years of professional experience and was reclassified as an Administrative Officer II. Her salary increased correspondingly to the top of that grade. She remained in that classification until she resigned effective July 31, 1977.
. Defendant also appeals from the clerk of court’s disallowance of costs for failure to file a bill of costs within ten days after notice of entry of judgment pursuant to local rule XXIII-A—4. Defendant moves this court to require the district court to consider its motion for retaxation of costs. Notice of entry of judgment was given on December 27, 1979. The bill of costs was not filed until January 10, 1980. We find no abuse of discretion in denying the defendants’ bill of costs.
. The dissent raises many arguments not briefed or urged by appellant in her brief. It is fundamental that it would be improper to decide this case on grounds not raised in the district court. The main thrust of the dissent is (1) that appellant possessed administrative experience entitling her to a higher classification and (2) that the State Board’s classification system was not job related. Appellant raised neither argument in her brief or in the trial below. Plaintiff did not assert at trial or on this appeal that she possessed the education or *104experience requirements of an Administrative Officer II at any time during her employment prior to July 1, 1977. Additionally, she does not claim that the state-wide classification system was not reasonably related to her job or that the classification creates a discriminatory impact on females over males. In any event, both of these classification evaluations fell within the exclusive jurisdiction of the State and it is difficult to assess how these defendants can be held responsible for something over which they had no control.