In its recent decision in JS v Secretary of State for Work and Pensions (Child Maintenance Assessments - Calculations)  UKUT 296 (AAC) the Upper Tribunal has read regulation 50 the same way as I did. The Upper Tribunal overturned the First Tier Tribunal's decision that the father did not share day to day care care because he had the child for only 172 nights a year. The overnight care arrangements were not determinative of the question of whether the 'day to day care' was equally shared and the First Tier Tribunal had placed too much weight on the overnight stays.
The decision in the JS case does not determine whether the effect of the shared care arrangement being equal is that there is CMS jurisdiction to make an assessment but the assessment is nil or whether it removes the case from the jurisdiction of the CMS at all. The former view seems to be implied by the Upper Tier Tribunal's judgment but it was not an issue which fell for decision in that case. It is an important issue, however, for the reasons explained in my earlier piece in 2015. If the CMS has no jurisdiction in a case of equally shared care then the court will have jurisdiction to make a child maintenance order, which will not be solely constrained by the statutory tests under the Child Support Act 1991. That important issue remains to be resolved by the courts.