The four task dependency types
A dependency says how one task's timing relates to another's. There are four types, and lag or lead fine-tunes them.
Finish to start (FS)
Pour the foundation, then build the walls. Most common.
Start to start (SS)
Start testing a day after development starts.
Finish to finish (FF)
Documentation cannot finish before the feature does.
Start to finish (SF)
The old shift cannot end until the new shift starts. Rare.
Lag and lead
Lag adds waiting time: concrete needs 3 days to cure after pouring (FS+3). Lead lets tasks overlap: painting can start 2 days before plastering ends (FS-2).
Good habits
- Use FS unless the work genuinely overlaps.
- Prefer lag for real waiting, not for padding.
- Avoid circular links; a plan cannot loop back on itself.
In GenuinePlan, enter 3SS+1 in the predecessors cell. See dependencies and lag and how they drive the critical path.
Frequently asked questions
Which dependency type should I use by default?
Finish to start. Reach for the others only when the work really overlaps.
Related
Dependencies and lag
Real projects overlap. Link tasks the way the work actually flows, with a lead or lag where it helps.
Read more →Critical path method
The critical path is the longest chain of dependent tasks. It sets the shortest possible project duration.
Read more →What is a WBS?
A WBS divides the total scope of a project into smaller, manageable pieces, so each can be estimated, assigned and tracked.
Read more →Plan your first project in a few minutes.
Free to start. Upgrade when you outgrow it.