Define: Constraint Type

Contraint type: A task scheduling option that determines how project tasks interact with each other with respect to dates.


Microsoft Project allows you to set constraint types for each task.  Using task constraints can really bugger up a project, if you don’t know what you are doing.  Ever hear of scheduling conflicts?  Consider using deadlines instead.  I feel constraints can be useful when used in moderation.  But most managers do not need to dive this deeply into task management.  Why?

Most projects change rapidly from day to day.  Because of this, you may find yourself fiddling with esoteric task options, only to find that they become irrelevant next week when the schedule changes.  That’s where deadlines can be simpler.

Here are the task constraints MS Project offers:

  1. As Late As Possible (default in a project scheduled from the finish date)
  2. As Soon As Possible (default in a project scheduled from the start date)
  3. Finish No Earlier Than
  4. Finish No Later Than
  5. Must Start On
  6. Must Finish On
  7. Start No Earlier Than
  8. Start No Later Than

 Clearly, these options control the behaviour of tasks that are linked together.  Let’s say you chose the “Start No Later Than” constraint type.  In this case, you would be required to supply a date that the task cannot start after.  Let’s say you chose August 1st.

A scheduling conflict can occur if a predicessor task causes your task to start after August 1st.  Schedules change so frequently that this is likely to happen.  Actually that can be a good thing.  Consider it an alert that something has gone wrong with your project.  If your project slips so badly that these contraints become activated, it can alert you to deeper problems witn your project team.