What is a significant factor affecting software development that leads to additional costs?

A significant factor affecting software development that leads to additional costs is new and changed system requirements. This can occur due to various reasons, such as evolving business needs, feedback from stakeholders, or changes in technology. When these requirements change after the development process has begun, it often necessitates revisiting and modifying existing work, which can lead to increased development time and costs.

Handling new or modified requirements usually requires additional resources, including time spent on revising designs, re-implementing features, and retesting the software. It may also lead to delays in the overall project timeline, affecting schedules and budgets. Therefore, managing requirements effectively is crucial in software development to minimize unexpected expenses and ensure that the project stays on track.

While underestimating user requirements, poor communication among team members, and lack of documentation can also certainly lead to issues in software projects, they contribute to problems in different ways and may not directly lead to the kind of extensive rework and cost increases that come with changing system requirements.