No project ends with exactly the requirements it started with. New insights, changed priorities and new regulations change the scope. That is normal. It becomes a problem when changes slip silently into the project and in the end nobody can explain why budget and schedule no longer hold.
What a change request contains
A description of the desired change, the rationale and expected benefit, the impact on scope, cost, schedule, quality and risk, affected deliverables and dependencies, and a recommended decision. The impact analysis is the core: without it, a change is decided whose price nobody knows.
Who decides
The decision must lie with a body authorised to bear the consequences — depending on the project, the client, a steering committee or a change board. Small changes within defined tolerances can be decided by the project manager. Who decides what should be settled at the start, for example in a RACI matrix.
In fixed-price projects
With a fixed price, the agreed scope is the basis of the price. Every extension therefore needs a change request with price and schedule impact before it is implemented. That protects both sides: the client from surprises, the supplier from unpaid extra work. The prerequisite is a cleanly described baseline scope, for example in a functional specification with verifiable requirements.
In agile projects
In agile projects, change is part of the model: new requirements go into the backlog, and prioritisation decides what is built. Formal change requests are then needed mainly for changes to the frame — budget, deadlines, goals or contractual agreements. Good requirements engineering records what changed and why here too.
Common mistakes
Changes on request without impact analysis. Many small changes that seem harmless individually and together expand the scope considerably. Decisions without documentation. And a process so cumbersome that it is bypassed. A good change process is quick for small changes and thorough for large ones. External project management brings in this process where it is missing.