How does the Child Maintenance Service decide on equal shared care?

When both parents are looking after their children for equal amounts of time neither of them should be assessed by the Child Maintenance Service (CMS) to pay maintenance.  Equal care is not just equal numbers of overnights – it relates to day-to-day care. If there is a dispute about whether maintenance should be due,  the CMS sometimes wrongly presumes that the parent who receives child benefit should receiving maintenance.  But according to an Upper Tribunal Decision evidence provided about the equality of day-to-day care by both parents can be used to decide neither parent pays maintenance even when one of them is in receipt of child benefit.  See also this decision and  this decision