s. 9 of the Federal Child Support Guidelines provides:
9 Where a spouse exercises a right of access to, or has physical custody of, a child for not less than 40 per cent of the time over the course of a year, the amount of the child support order must be determined by taking into account
As a "starting point", the court will first assess whether the amount determined according to a simple "set-off" is appropriate. The "set-off" calculation is the calculation that is applicable in the "split" custody scenario. In many cases, the "set-off" amount will be appropriate unless one party brings sufficient evidence that this amount is inappropriate. The figures to input into the "set-off" are determined in reference to the party's income, the number of children, and the British Columbia Child Support Tables.
An example of the analysis is contained in the case of C.L.B. V. A.H.B., 2013 BCCA 472 (CanLII).
I will provide the pertinent excerpts from this judgment as follows:
 The parties were married in 2007, separated in 2011, and were divorced on August 31, 2012. There is one child of the marriage who was born on August 13, 2007. The final order for corollary relief was granted on December 19, 2012, and included the following orders:
(i) Joint custody and joint guardianship of the child of the marriage based on a week-about shared custody arrangement;
(ii) Section 9 Federal Child Support Guidelines, SOR/1997-175 (“Guidelines”) support [in a shared custody arrangement] payable by the appellant in the monthly amount of $690, based on the net difference between the s. 3 Table amount payable by the appellant on a Guidelines income of $109,731 and the Table amount payable by the respondent based on a Guidelines income of $34,202;
(iii) Section 7 Guidelines support for the child’s special and/or extraordinary expenses to be shared equally between the parties; and
(iv) Spousal support payable by the appellant in the monthly amount of $1,210, being at the low end of the range of spousal support under the Spousal Support Advisory Guidelines (“SSAG”) - between $1,210 and $1,954 - based on the parties’ respective Guidelines income and the appellant’s child support obligation;
[the “Final Order”].
 I would also observe that while the trial judge adopted the set-off approach from s. 9(a) of the Guidelines, the Court in Contino v. Leonelli-Contino, 2005 SCC 63,  3 S.C.R. 217, stated that the simple set-off serves as only a starting point for the inquiry into the appropriate amount of child support in a shared custody arrangement, observing at para. 49:
 Hence, the simple set-off serves as the starting point, but it cannot be the end of the inquiry. It has no presumptive value. Its true value is in bringing the court to focus first on the fact that both parents must make a contribution and that fixed and variable costs of each of them have to be measured before making adjustments to take into account increased costs attributable to joint custody and further adjustments needed to ensure that the final outcome is fair in light of the conditions, means, needs and other circumstances of each spouse and child for whom support is sought. Full consideration must be given to these last two factors (see [Julien D. Payne and Marilyn A. Payne, Child Support Guidelines in Canada 2004 (Toronto: Irwin Law, 2004).] at p. 263). The cliff effect is only resolved if the court covers and regards the other criteria set out in paras. (b) and (c) as equally important elements to determine the child support. [Emphasis in original.]
 The Court in Contino went on to address ss. 9(b) and (c). In regard to s. 9(b) - the increased costs of shared custody arrangements - the Court underscored the need for evidence of the actual spending patterns of the parents and the need by the payor parent to demonstrate that his or her increase in the actual time spent with the child directly results in additional costs for him or her (para. 53). The Court stated:
 What should the courts examine under this heading? Section 9(b) does not refer merely to the expenses assumed by the payor parent as a result of the increase in access time from less than 40 percent to more than 40 percent … Consequently, all of the payor parent’s costs should be considered under s. 9(b). This does not mean that the payor parent is in effect spending more money on the child than he or she was before shared custody was accomplished. … it means that the court will generally be called upon to examine the budgets and actual expenditures of both parents in addressing the needs of the children and to determine whether shared custody has in effect resulted in increased costs globally. Increased costs would normally result from duplication resulting from the fact that the child is effectively being given two homes. [Emphasis in original.]
 In regard to s. 9(c) - the conditions, means, needs and other circumstances - the Court underscored the need for evidence from the parties on these factors (stating that “courts should demand information from the parties when it is deficient” [para. 57]) and not make assumptions about increased costs (para. 56). It stated:
 Section 9(c) vests the court a broad discretion for conducting an analysis of the resources and needs of both the parents and the children. As mentioned earlier, this suggests that the Table amounts used in the simple set-off are not presumptively applicable and that the assumptions they hold must be verified against the facts, since all three factors must be applied. Here again, it will be important to keep in mind the objectives of the Guidelines mentioned earlier, requiring a fair standard of support for the child and fair contributions from both parents. The court will be especially concerned here with the standard of living of the child in each household and the ability of each parent to [absorb] the costs required to maintain the appropriate standard of living in the circumstances.
 Moreover, given the broad discretion of the court conferred by s. 9(c), a claim by a parent for special or extraordinary expenses falling within s. 7 of the Guidelines (see Appendix) can be examined directly in s. 9 with consideration of all the other factors (see Slade v. Slade, [(2001), 195 D.L.R. (4th) 108, 2001 NFCA 2] at paras. 26-30). Section 9(c) is conspicuously broader than s. 7.
In the result, the court ordered that the quantum of child support was to be determined according to the "set-off" formula:
 Based on a Guidelines income of $86,762, the Table amount of child support would be $796. From this amount, applying the set-off formula adopted by the trial judge for the shared custody arrangement (which was not appealed and therefore must be assumed to be correct), the respondent would be entitled to s. 9 Guidelines support of $477.