Start-to-finish (SF)
A start-to-finish (SF) dependency means the successor cannot finish until its predecessor has started. It is the rarest dependency type, used where old work must continue until new work begins.
The classic case is a handover: support for an old system has to continue until the new system goes live, so the old support finishes only when the new system starts.
Like start-to-start, SF looks at the predecessor's start, so a predecessor that starts on time but finishes late does not move its SF successor.
Worked example
| Task | Duration | Depends on | Scheduled | Total float |
|---|---|---|---|---|
| 1. Cutover | 5 days | None | Days 1 to 5 | 0 days |
| 2. Run new system | 10 days | 1 | Days 6 to 15 | 0 days |
| 3. Legacy support | 6 days | 2SF | Days 1 to 6 | 9 days |
Run new system starts on day 6, after the cutover. Legacy support cannot finish before then, so it runs days 1 to 6 and ends on the day the new system starts.
Open this example in the free delay simulator to change the durations, the links or the delay and watch the schedule move.