The number nobody owns
Every company can tell you its headcount cost. Very few can tell you what it costs when a specific senior person leaves, and fewer still separate the part that is recruitment spend from the part that is lost output. So senior attrition sits in the accounts as a recruiting invoice, which is the smallest component of it, and the rest never appears anywhere.
That matters because the interventions that reduce it are judged against the visible number. If the only cost you can name is the search fee, then anything that costs more than a search fee looks unjustifiable, and the conversation ends there.
The four components
Work it out in four parts. Replacement is the search fee, internal recruiter time, and the hours your existing executives spend interviewing. Vacancy is the period the seat is empty and the work is either not done or absorbed by people already at capacity. Ramp is the months between a start date and full effectiveness, which for a senior hire is measured in quarters rather than weeks. And the fourth is the one that never gets counted: the decisions that were deferred while the seat was empty and while the new person was learning the business.
The first three are arithmetic. The fourth is judgement, and it is usually the largest.
Doing it with your own numbers
Take one role you have actually lost in the last two years. Write down the loaded annual cost of that seat. Then answer four questions about that specific departure. How many months was the seat empty. How many months until the replacement was operating at the level of the person who left. What did you pay externally to fill it. And which decisions waited.
Multiply the loaded monthly cost by the vacancy months, add half the loaded monthly cost for each ramp month, add the external spend, and you have a defensible floor. It is a floor because it excludes the fourth component entirely.
Do this for three departures and you will have a number for your own business that no benchmark can give you, and one that survives a CFO asking where it came from.
Why the causes matter more than the total
A total tells you the size of the problem. It does not tell you which lever moves it. The reason to split senior attrition by cause is that the causes have very different remedies, and two of them are routinely misfiled.
Departures that get recorded as a better offer elsewhere are sometimes exactly that. Others are a person who had already decided months earlier, for reasons that were physiological before they were professional: sustained sleep debt, a metabolic decline nobody named, or a hormonal transition that a senior woman was managing alone because there was no way to raise it. Those get exit-interviewed as career progression, because that is the answerable version.
You cannot fix what you have miscoded. The practical step is not a new policy, it is asking the question in a form people can answer honestly.
Where this goes next
The calculation above is the part you can do this week without us. What it does not give you is the second half: which biological windows actually drive senior-level attrition, what a company can influence and what it cannot, and how to build the case internally without turning it into a wellbeing programme that changes nothing.
That is what the company track covers, with the sponsoring CHRO in the room rather than briefed afterwards.
This article is the public half. Expand Education for companies is where the rest of it lives.