Short answer
It usually sits in HR and pays back in operations. That split is why leadership development often gets cut first: it’s judged as a training expense rather than on what it changes. Scope it around an operating problem, like slow handoffs, repeat decisions, escalations or turnover among managers, and measure the result in those terms. That gets the COO and CHRO behind the same number.
The longer answer
In owner-led companies the CEO often decides directly. In larger ones, the CHRO or head of L&D usually runs the process, and the COO decides whether it matters. Getting both into the conversation early saves months.
Our diagnostic is built for that: it gives HR a clear development need and gives operations a cost figure from its own numbers.