CMS 50/50 shared care: what actually matters?
A 50/50 parenting arrangement does not always reduce a CMS dispute to a simple count of nights. The legal and factual position can depend on how care is actually shared, what decision CMS has made and what evidence supports the day-to-day arrangements.
Search the Upper Tribunal case libraryOvernight stays and equal care are not the same question
CMS calculations commonly use overnight stays when applying shared-care reductions. But some disputes concern a wider question about whether both parents are providing care in substantially equal terms. Those issues should not automatically be treated as identical.
If your dispute is specifically about equal day-to-day care, identify the exact CMS decision and the rule CMS says it has applied before arguing only about the number of nights.
Evidence that may help
Useful evidence can include a child arrangements order, a care calendar, school or nursery records, medical appointments, childcare arrangements, correspondence between parents and records showing who deals with the practical responsibilities of care.
The strongest evidence usually shows what actually happens over time rather than relying on one label, address or isolated document.
If CMS makes a decision you disagree with
You can normally ask CMS to reconsider a child maintenance decision through mandatory reconsideration. Your decision letter should explain the route and deadline. GOV.UK currently says a challenge is generally requested within 30 days of the date on the CMS decision letter.
After a mandatory reconsideration notice, an appeal may be available to the independent Social Security and Child Support Tribunal.
Check the law and the cases
CMS Support UK keeps community experiences separate from authoritative legal material. Our Upper Tribunal library contains decisions involving shared care and related CMS disputes, with plain-English summaries and links to the official judgments.
Official information: GOV.UK CMS complaints and appeals. Always check the latest decision letter and official guidance before acting.
More CMS guides
Continue with the part of the CMS process that applies to your situation.