MoSCoW Prioritisation — Why "Must Have" Ends Up Meaning Everything

What is MoSCoW prioritisation?

MoSCoW is a prioritisation technique that assigns each requirement to one of four categories: Must Have, Should Have, Could Have, and Won't Have (this time). It was developed by Dai Clegg at Oracle in the 1990s and remains the most widely used requirements prioritisation method in business analysis.

• Must Have: Non-negotiable. The solution is not viable without this requirement. Removing it would mean the project should not launch.
• Should Have: Important but not critical. The solution works without it, but with reduced value. Should be included if at all possible.
• Could Have: Nice to have. Low impact if absent. Included only if time and budget permit.
• Won't Have (this time): Explicitly agreed not to include in this release. Important to document — it manages expectations and prevents scope creep.

Why MoSCoW fails in practice

In most projects, 80-90% of requirements end up classified as Must Have. When everything is Must Have, nothing is prioritised. The technique has failed to do its job.

This happens for three reasons. Stakeholders are afraid that if they classify something as Should Have, it will never be built. Facilitators do not enforce the constraint that Must Have should represent no more than 60% of planned effort. And nobody defines what "viable" means — so Must Have becomes a personal preference rather than a business necessity.

How to run an effective MoSCoW workshop

Before the workshop: Define what "viable" means for this project. What is the minimum the system must do for the business to operate? This is your Must Have baseline. Document it and share it before the workshop so stakeholders arrive with a shared understanding.

During the workshop: Present each requirement and ask a single test question: "If this requirement is not delivered, should we still launch?" If the answer is no, it is Must Have. If the answer is yes, it is Should Have or Could Have.

When a stakeholder says everything is Must Have, try the budget test: "If we had to cut 30% of the budget tomorrow, what would you remove?" The answer reveals what they actually value most.

After the workshop: Publish the agreed MoSCoW list with the rationale for each classification. Get it signed off. When scope pressure arrives — and it will — the signed MoSCoW is your evidence for what was agreed.

Enforcing MoSCoW throughout the project

Prioritisation agreed in a workshop will be challenged in the build. "This was a Should Have but now we realise it is essential" is a common and sometimes legitimate request. Handle it formally: if a Should Have is promoted to Must Have, a Must Have must be demoted or the timeline extends. The MoSCoW is not a one-time exercise — it is a dynamic tool for managing scope throughout delivery.