An information technology department grows through four recognisable stages and each one adds a layer rather than a role. This page is those four stages, what each layer is for, and the headcount that triggers it. The value of naming the stages is that they let you hire ahead of a boundary rather than after it: almost every painful IT reorganisation is a department that stayed in stage two while the company moved into stage three. The arithmetic is the company's own, and the planner prints the managers and layers your headcount implies at whatever span you run.
Stage one and two: one person, then a queue with an owner
One person is the whole department and the chart is a name. The second stage arrives at three or four people, when the queue needs an owner so engineering work stops being interrupted, and the layer that appears is a manager who still does the work. Nothing else changes: one group, one line, and the chart's job is publishing the queue's owner to the rest of the company.
Stage three: three groups under one manager
Somewhere around eight people the department splits into service desk, infrastructure and applications. That is the first real structure and it is still one layer of management over three groups, comfortably inside a span of seven. This is the stage most companies of a hundred to two hundred people sit in, and it holds well as long as security has a name against it.
Stage four: leads, and a second layer
Past fifteen or so, each group gets a lead and the head of IT stops doing the work. The department now has two layers and about five people per lead, and the dotted lines into finance, legal and product become permanent enough to draw. On the worked example each of those standing relationships costs roughly a fortnightly half hour, which is the price of the coordination the structure created.
Questions people ask about information technology department structure
Does this differ for a company with no engineering team?
The applications group is larger and infrastructure smaller, but the stages and the boundaries are the same.
When should we outsource part of it?
Usually the out-of-hours queue first. Whoever provides it goes on the chart as an external box, or the chart is not a picture of who answers.
Where does data or analytics sit?
Rarely in IT past stage three; it usually follows the business function that owns the numbers, with a dotted line back for platform support.