The time-phased budget is the schedule (plan) for expenditure of the resources necessary to accomplish program work scope requirements. The budget for a period is compared to the earned value for the same period to determine and quantify the schedule performance for the program. The resultant metric is the schedule variance. It represents the quantity, i.e., the value, of the work that is ahead of or behind schedule. The specific activities and events that are contributing to the variance can be identified in program schedules.

In Earned Value Management (EVM), schedules contain time-phased budgets for resources. Expenditures of time-phased budgets are compared to accomplishment of work scope requirements. The comparison is a metric that is called “schedule variance”. Schedule variance provides early insight of detail and overall schedule performance.

 Schedule Variance (SV) = Accomplishment (Earned Value) – Time-phased budget.

This is often shown as SV = Budgeted Cost of Work Performed (BCWP) – Budgeted Cost of Work Scheduled (BCWS)