The three layers of running cost

The three layers of running cost split what a software system costs after go-live into infrastructure (databases, storage, media), availability (keeping the system working, with the response-time commitment as the price variable), and development (new capability). The first two are unavoidable; the third is discretionary — it exists because the business sees a way to work faster, not because the system decays without it.

Why it matters

A single "maintenance and support" line hides the one decision a buyer can actually make: what to dial down without breaking anything. Split into layers, the running cost becomes negotiable — storage is arithmetic, the response-time commitment is a choice, and the development budget can be declined for a quarter without consequence.

Common confusion

The three layers are not a maintenance fee expressed three ways. A vendor who folds development into "maintenance" has merged a choice with an obligation — the buyer loses the ability to say "not this quarter."

Where we use it

The framework carries What a quoting system costs to run, and the contract checklist asks for the retainer itemized by layer.