The decision in OS v DT [2025] EWFC 156 (B), given by HHJ Hess and certified as citable, marks a significant development in child maintenance law where parents share the care of their children “exactly equally”.
Although the case arose from a high-value financial remedies dispute, its wider importance lies in clarifying when the court, rather than the Child Maintenance Service (CMS), has jurisdiction to make child maintenance orders where there is an exactly equal shared care arrangement.
The shared-care problem
Under the Child Support Act 1991, courts are usually barred from making child maintenance orders where the CMS has jurisdiction.
However, regulation 50 of the Child Support Maintenance Calculation Regulations 2012 creates a unique situation in cases of exactly equal shared care. The CMS can only act where one parent provides less day-to-day care than the other. Where care is truly equal, there is no “non-resident parent” and therefore no CMS assessment can be made.
For years, it was unclear whether this meant:
- the CMS still had jurisdiction but would assess maintenance at £0, or
- the CMS had no jurisdiction at all, leaving the court free to act.
OS v DT finally answers this.
What HHJ Hess decided
HHJ Hess held that:
- In cases of exactly equal shared care, the CMS has no jurisdiction under regulation 50.
- Because the CMS cannot act, the statutory bar in sections 8(1) and 8(3) of the Child Support Act 1991 does not apply.
- The court therefore retains its residual power under section 23(1)(d) of the Matrimonial Causes Act 1973 to make a child periodical payments order.
Crucially, he also ruled that a party does not have to apply to the CMS first. The court itself can decide whether care is equal and proceed on that basis.
This provides long-awaited clarity in an area that had been uncertain since the 2012 regulations came into force.
The outcome in OS v DT
Although jurisdiction was established, the court declined to order child maintenance on the facts. The parents shared care equally and both emerged from the proceedings with substantial capital (just over £3.44m each), as well as strong earning capacity.
HHJ Hess concluded that periodical payments were not necessary or fair. Instead, the court made a targeted child-related order: the father was to meet 75% of the children’s school fees, reflecting his greater resources and earning capacity.
The case therefore shows that even where regular maintenance is inappropriate, the court can still make bespoke financial provision for children once jurisdiction is established.
Why the decision matters
OS v DT has two major practical consequences.
First, it confirms that in true shared-care cases the court, not the CMS, is the proper forum for child maintenance disputes. This effectively creates a third category of cases alongside ordinary CMS claims and “top-up” applications for high earners.
Secondly, it is likely to lead to more disputes about whether care is exactly equal. Establishing equal care now carries real legal significance: it removes the CMS from the picture and reopens the court’s powers. That may encourage litigation over care arrangements, not just for welfare reasons but also for jurisdictional advantage.
What remains unresolved
While OS v DT settles the question of who decides, it leaves open how courts should decide how much maintenance to order in shared-care cases. Traditionally, judges have used the CMS calculation as a starting point. Here, the CMS would do nothing at all.
Future cases will need to develop clearer principles on:
- assessing need where care is equal,
- reflecting shared parenting in quantum, and
- achieving consistency between courts.
Conclusion
OS v DT is a significant decision on child maintenance and shared care. It establishes that where parents have exactly equal care, the CMS has no jurisdiction and the court’s powers revive — and that parties can go straight to court without first applying to the CMS.
The judgment brings clarity to a long-uncertain area of law, but it also shifts the battleground. Disputes are now more likely to focus on care patterns and jurisdiction, shaping how shared-care maintenance cases are argued from the outset.
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