MoSCoW Prioritisation

What the four categories mean

The definitions only work if they are applied strictly. Loosely applied, everything becomes a Must and the exercise has achieved nothing.

Must have

Without this, the release has no value or cannot legally or safely ship. The test is whether you would delay the launch for it.

Should have

Important and painful to omit, but there is a workaround. The release still delivers value without it.

Could have

Desirable, low impact if dropped. The first thing to go when time tightens.

Won't have

Explicitly out of scope this time. Recorded rather than merely absent - which is the whole point.

Why the fourth category is the valuable one

Most prioritisation methods produce a ranked list of what you will do. MoSCoW also produces a written record of what you decided not to do, which is exactly the thing that is missing when a client later remembers a feature as included. On fixed-fee work, the Won't have list is functionally the exclusions section of your agreement.

The failure mode

Everything becomes a Must have, usually because stakeholders read Should as "will not happen". The countermeasure is a budget: cap Musts at a defined share of capacity - commonly around 60% - so the categories stay meaningful and there is real contingency. If the Musts alone exceed capacity, the plan is already broken and the categorisation has usefully told you so.