
152 S.W.3d 447 (2004)
Synthia M. HOPKINS
v.
Victor L. HOPKINS.
Supreme Court of Tennessee, at Nashville.
Heard[1] June 2, 2004 Session.
September 27, 2004.
Sharon T. Massey and Gregory D. Smith, Clarksville, Tennessee, for the appellant-defendant, Victor L. Hopkins.
Mark A. Rassas and Julia P. North, Clarksville, Tennessee, for the appellee-plaintiff, Synthia M. Hopkins.
Heard at Cookeville[1] June 2, 2004.


*448 OPINION
JANICE M. HOLDER, J., delivered the opinion of the court, in which FRANK F. DROWOTA, III, C.J., and E. RILEY ANDERSON, and ADOLPHO A. BIRCH, JR., JJ., joined. WILLIAM M. BARKER, J., filed a dissenting opinion.
The issue in this case is whether child support may be awarded when neither party has been designated the primary residential parent. The Court of Appeals modified the trial court's judgment to award equal parenting time between the parties. Neither party contests this modification. We hold that the Court of Appeals erred, however, in awarding child support to one party when neither party was designated the primary residential parent. We remand to the trial court for the designation of a primary residential parent, for the consideration of the amount of child support to be paid, and for entry of a parenting plan.

Factual and Procedural Background
In January 2001, Synthia M. Hopkins ("Mother") filed a complaint seeking a divorce from her husband, Victor L. Hopkins ("Father"). Father filed an answer and counter-complaint. Both parties filed proposed parenting plans in the trial court. Father submitted two parenting plans, one more detailed than the other. Both plans filed by Father called for the parties to divide the residential schedule of their three minor children equally, and the second plan required Father to pay Mother $800 per month in child support. Mother's parenting plan listed her as the residential custodian of the three children and required Father to make child support payments in the amount of $1,262.15 per month.
In July 2002, the trial court granted Mother a divorce on the ground of inappropriate marital conduct. The trial court did not adopt a parenting plan proposed by either party. Although the trial court stated that it was adopting its own parenting plan, no formal parenting plan was signed by the parties or set forth in the final divorce decree. In its ruling, the trial court found that the demands of Mother's master's degree program, when combined with her full-time teaching position, would necessarily limit the time she had available to meet her children's needs. The trial court found that Father's job was flexible and that he needed no further education. The trial court's divorce decree, in effect, granted primary physical custody of the parties' three children to Father. Mother was ordered to pay child support to Father in the amount of $681.37 per month. The children were ordered to reside with Father during the school year and with Mother during the summer. Mother objected to the residential schedule and filed a Motion to Alter and Amend, in which she stated that she would be pursuing her master's degree studies on a part-time basis and that her class schedule would take away only limited parenting time. The motion was denied. Mother subsequently appealed.
The Court of Appeals reversed the trial court's residential provisions and its child support ruling. The intermediate appellate court adopted one of the parenting plans submitted by Father. The court thus divided the residential schedule of the children between Mother and Father equally, with both parties alternating physical custody on a weekly basis. This alternating custody arrangement is greatly facilitated by the fact that Father built a house next door to the marital home where Mother resides. In addition, Father was ordered to pay child support to Mother in the amount of $800 per month, the amount Father suggested to the trial court in one *449 of his parenting plans. The court did not designate a primary residential parent.
Father asserts that the Court of Appeals erred in determining the proper amount of child support. We granted permission to appeal.

Analysis
It is important to note that neither party takes issue with the Court of Appeals' determination that the parties should share equal time with their children. The only issue before us is that of support. Father argues that the Court of Appeals erred in calculating his child support obligation. He proposes two alternatives for determining the proper amount of child support in a case in which custody of minor children is divided equally between two parents. First, Father suggests that the income of both parents be considered in calculating the child support award. Second, Father suggests that neither party should be required to pay child support.
In Gray v. Gray, 78 S.W.3d 881, 882 (Tenn.2002), we held that "the use of a comparative analysis of the parties' earnings is improper under the Child Support Guidelines." Under the Child Support Guidelines applicable in the present case, the income of the obligee (the parent with whom the children primarily live) is not to be considered in the calculation of the amount of child support awarded. Tenn. Comp. R. & Regs. 1240-2-4-.03(2). Thus, we reject Father's suggestion that the income of both parties should have been considered in computing child support.[2]
Father's second suggestion is equally flawed. Child support payments are for the benefit of the child, and both parents have a duty to support their minor children. See, e.g., Gallaher v. Elam, 104 S.W.3d 455, 461 (Tenn.2003). We decline to adopt a bright-line rule that no child support is owed when a child's residential time is divided equally between the parents.
The Child Support Guidelines do not expressly provide for an equal division of residential time. Instead, the Guidelines address situations in which a child resides primarily with one parent. See Tenn. Comp. R. & Regs. 1240-2-4-.02(6) (providing that the Child Support Guidelines "are designed to apply to situations where children are living primarily with one parent but stay overnight with the other parent at least as often as every other weekend from Friday to Sunday, two weeks in the summer and two weeks during holidays throughout the year"). Accordingly, a primary residential parent is defined as "the parent with whom the child resides more than fifty percent (50%) of the time." Tenn.Code Ann. § 36-6-402(4) (2001) (emphasis added). However, we do not interpret this definition as precluding a child's residential schedule from being divided equally between the parents. While silent on this precise issue, the Guidelines "are designed to consider the actual physical custody of the child(ren), regardless of whether custody is awarded to one parent and visitation to the other or such an arrangement is ordered to be joint custody or split custody." Tenn. Comp. R. & Regs. 1240-2-4.02(6).
Having decided that an equal division of time is permissible under the Guidelines, we must address the manner in which child support is to be calculated in such a situation. In situations in which *450 overnight time is divided more equally between the parents, courts should make a case-by-case determination as to the appropriate amount of support. Tenn. Comp. R. & Regs. 1240-2-4-.02(6); see also Gray, 78 S.W.3d at 884; Tenn. Comp. R. & Regs. 1240-2-4-.04(2)(b). Therefore, it may be appropriate to award less child support to the primary residential parent when residential time is divided equally.
In the present case, however, the Court of Appeals did not designate a primary residential parent. Tennessee's statutes require both a residential schedule, see Tenn.Code Ann. § 36-6-404(b) (2001), and the designation of a primary residential parent, see Tenn.Code Ann. § 36-6-402(5) (2001). As we stated in Gray,"the Child Support Guidelines contemplate that child support may be awarded only to the primary residential parent." 78 S.W.3d at 884. We hold that the Court of Appeals erred in awarding child support without designating a primary residential parent.[3]
We affirm the Court of Appeals' determination and the parties' desire that the parents share equal residential time. However, we vacate the intermediate court's award of child support. We remand this case to the trial court to determine which party should be designated the primary residential parent. The trial court must then apply the Child Support Guidelines to determine the amount of child support, if any, that the non-primary residential parent should pay to the primary residential parent.[4] Finally, the trial court should direct the parties to submit to the court a permanent parenting plan that incorporates the requirements set forth in Tennessee Code Annotated section 36-6-404.

Conclusion
In summary, we hold that under the Child Support Guidelines, only the primary residential parent may be awarded child support. In reviewing the trial court's judgment, the Court of Appeals erred in failing to designate a primary residential parent. We remand this case to the trial court for further proceedings consistent with this opinion. On remand, the trial court shall consider all of the relevant statutory factors in designating a primary residential parent and in calculating child support and shall enter a parenting plan. Costs of this appeal are taxed equally to the appellant, Victor L. Hopkins, and the appellee, Synthia M. Hopkins, and their sureties, for which execution may issue if necessary.
WILLIAM M. BARKER, J., filed a dissenting opinion.
WILLIAM M. BARKER, J., dissenting.
With its decision today, the majority has attempted to fit a round peg into a square hole, and as one would expect, it does not fit.
The sole issue in this case is whether the award of child support of $800 per month *451 to be paid by the father is appropriate. Neither party has appealed the Court of Appeals' custody determination. While not specifically at issue, a brief review of the custody situation is helpful.
The trial court granted primary custody of the parties' three children to the father, who would have custody approximately 230 days per year, and the mother would have custody the remaining 135 days per year. The mother was ordered to make child support payments to the father in the amount of $681.37 per month. The Court of Appeals reversed the trial court's custody determination and adopted the parenting plan that had been proposed by the father. Pursuant to that plan, both parents would share equal custody, alternating custody on a weekly basis.[1]
The parenting plan adopted by the Court of Appeals also provided that the father would pay child support in the amount of $800 per month to the mother. The Court of Appeals found that this approximately equaled the amount of support the father would owe under the guidelines minus the amount the mother would owe under the guidelines.
The Child Support Guidelines were "designed to apply to situations where children are living primarily with one parent but stay overnight with the other parent at least as often as every other weekend from Friday to Sunday, two weeks in the summer and two weeks during holidays throughout the year." Tenn. Comp. R. & Regs. 12-2-4-.02(6). The guidelines consider "actual physical custody of the child(ren), regardless of whether custody is awarded to one parent and visitation to the other or such an arrangement is ordered to be joint custody or split custody." Id.
While the guidelines do allow for downward deviation of support where custody is divided more equally between the parents, Tenn. Comp. R. & Regs. 12-2-4-.02(6), support is still granted to the parent with whom the child(ren) live primarily, Tenn. Comp. R. & Regs. 12-2-4-.03. In other words, it is always presumed in the guidelines that one parent will have more than 50% of the custody of the child(ren). Nowhere in the guidelines is there direction for providing support where custody is divided exactly equally.
The majority of this Court has approved the Court of Appeals' decision to award equal custody to the parents, but also recognizes that under the guidelines, support can only be granted to the "primary residential parent." Tenn. Comp. R. & Regs. 1240-4-.03(1), (2). The "primary residential parent" is, be definition, the parent with whom the child(ren) reside more than 50% of the time. Tenn.Code Ann. § 36-6-402(4) (2003 Supp.). Therefore, the majority is remanding the case to the trial court to name a "primary residential parent" for the sole purpose of awarding child support to one of the parents. This is a contrived result that stands the definition of "primary residential parent" on its proverbial ear.
Because the child support guidelines do not cover this situation in which the parents are sharing equal custody of the children, a better solution would be for the court to look to the law that was in existence prior to the enactment of the guidelines. Cf. In re Swanson, 2 S.W.3d 180, 189 (Tenn.1999) (holding that where part *452 of the statute relating to the abandonment of a child was found unconstitutional, the definitions that were in effect under the prior law would remain in effect until the legislature amends the statute); Leech v. Am. Booksellers Ass'n Inc., 582 S.W.2d 738, 740 (Tenn.1979) (holding that prior law is in full force and effect when an act is held unconstitutional).[2]
Prior to the adoption of the child support guidelines, the trial court was vested with wide discretion in matters relating to child custody and support. Campanali v. Campanali, 695 S.W.2d 193 (Tenn.Ct.App.1985). The obligation to provide support was found to be "determinable only by equitable principles and rules, with due regard to the condition and means of each [parent]." Brooks v. Brooks, 166 Tenn. 255, 61 S.W.2d 654, 654 (1933); Lescher v. Lescher, 679 S.W.2d 463, 465 (Tenn.Ct.App.1984).
Prior to the guidelines, Tennessee Code Annotated section 36-5-101(e) (1988) set forth the factors to be considered by the trial court when determining the necessity and amount of child support:
(1) The age, physical, mental and emotional condition of each child;
(2) The educational needs of each child and the educational advantages each child had available at the time the circumstances requiring a court order for his or her support arose;
(3) The earning capacity, obligations and needs, and financial resources of each parent;
(4) The contributions, monetary and nonmonetary, of each party to the well-being of the children;
(5) The financial resources of each child;
(6) The standard of living each child has enjoyed during the marriage; and
(7) Such other factors as are necessary to consider the equities for the parents and children.
Tenn.Code Ann. § 36-6-101(e) (1988). From among these factors, the need of the child(ren) and the parent's ability to pay should receive the foremost consideration. Allison v. Allison, 638 S.W.2d 394, 396 (Tenn.Ct.App.1982).
In approving of the child support of $800 proposed in the parenting plan, the Court of Appeals considered the needs of the children and the resources of each parent, concluding that the $800 would "equalize the resources available to the children, regardless of which parent they are with." The Court also noted that "if we were to subtract the presumptively correct amount of support [the mother] would be obligated to pay under the child support guidelines from the amount [the father] would have to pay under the same guidelines, the result would be very close to the amount [the father] offered." While the guidelines do not apply to this situation, and do not allow for the consideration of the obligee's income and resources, this simply demonstrates that the Court of Appeals was attempting to fashion an equitable child support award for this particular set of circumstances.
Because the child support guidelines do not cover this situation in which custody is divided equally between the parents, the court should revert to pre-guidelines equitable principles in setting child support. The Court of Appeals' decision appears to have done just that, and therefore, I would *453 affirm both the custody and child support determinations made by that Court.
NOTES
[1]  Oral argument was heard in this case on June 2, 2004, in Cookeville, Putnam County, Tennessee, as part of this Court's S.C.A.L.E.S. (Supreme Court Advancing Legal Education for Students) project.
[2]  We note, however, that proposed amendments to the Child Support Guidelines allow for a comparative analysis of the parties' incomes in determining child support. See Substance of Proposed Rules of the Tennessee Department of Human Services, Tenn. Comp. R. & Regs. 1240-2-4.
[3]  The designation of a primary residential parent is also important for purposes other than the determination of child support. For example, other state and federal statutes require that one parent be named the child's custodian. See Tenn.Code Ann. § 36-6-410 (2001).
[4]  Instead of applying the guidelines, the dissent would revert to "the law that was in existence prior to the enactment of the guidelines." The cases on which the dissent relies, however, involve statutes found to be unconstitutional. In this case, the constitutionality of neither the statute nor the guidelines has been raised by the parties or addressed by the dissent. The dissent cites to no case holding that difficulty in application warrants ignoring a statute in favor of "equitable principles."
[1]  While neither party challenges the custody arrangement, it is important to note that rarely is completely equal custody appropriate. That having been said, equal custody in this case is less problematic due to the fact that the parents live next door to each other, thus providing more stability for the children than would normally be available in other equal custody situations.
[2]  While these cases deal with statutes that were found to be unconstitutional instead of simply inapplicable, they do stand for the proposition that when a statute cannot be applied to a certain factual situation, the law prior to the enactment of that statute should be utilized. In re Swanson, 2 S.W.3d at 189; Leech, 582 S.W.2d at 740.
