Implementing Building Information Modeling (BIM) brings efficiencies to construction projects, yet evaluating the associated soft costs remains challenging. This study aims to develop and validate a framework for soft cost elements (SCEs) in BIM-based construction projects. A systematic literature review (SLR) and thematic analysis initially identified 31 SCEs, which were subsequently organized using framework analysis by project phase (planning, preconstruction, construction, and post-construction) and time category (discrete vs. continuous). Inter-rater reliability for the categorization reached 81.3%. Expert validation (n = 16) refined the framework and added seven BIM-specific SCEs, resulting in a total of 38. Theoretically, the framework extends soft-cost theory into the digital domain by modeling BIM-specific remuneration and overheads and by introducing a phase–time structure that explains when and how soft costs arise. Practically, it is operationalized as a decision tool: owners and quantity surveyors can use it as a checklist to create explicit budget lines, scope BIM roles, and update cadences in contracts, and monitor continuous costs monthly while tying discrete costs to milestones, thereby improving estimation accuracy, return-on-investment assessment, and risk control across the project lifecycle. To our knowledge, this is the first validated, phase–time SCE framework for BIM-based construction projects.