I would like to be able to set task constraints based on dates relative to other tasks, for instance:
"taskA to start no earlier than taskB end date + 20 days"
is there a way to do it? In MS Project I only shows absolute dates


1 Answer 1


You should be able to do this by linking tasks and creating dependencies between them.

From memory, while on the Gantt screen, ensure that the Predecessor column is shown. In the example you give, let's assume TaskB is in row 24 and TaskA is in row 25 of the page. In the "Predecessor" column of row 25, enter 24FS+20d.

There is an explanation here which gives you the basics of using MS Project (you will have to navigate through a couple of pages) although it may be slightly different for different versions of the application.

  • Thanks for your answer but to me it seems relative to something simpler than my question, it seems to be missing the "no earlier than". BTW I wonder whether a simple dependency as you suggest would have the same effect, at firtst sight it might seem so but I would need to be 100% sure before going for it, currently do notr feel 100% sure
    – user778806
    Commented Feb 3, 2021 at 20:17
  • 1
    The way you asked your question, @Iain9688's answer is 100% correct. FS+20 is the logic you would load in the predecessor field (adding the task row, of course). If there is another problem you're trying to solve, update your question. Commented Feb 4, 2021 at 15:03
  • If there are other dependencies on other tasks, MS Project will honour all of the dependency constraints. This will apply a "no earlier than" date to all of the individual dependencies.
    – Iain9688
    Commented Feb 4, 2021 at 17:07
  • To be a bit pedantic my question was about task constraints, that in MS project are not the same thing as task dependencies. As pedantry is not a good thing I will accept the answer and go for an FS even though there isn't any of the usual dependencies and a constraint seemed conceptually more appropriate.
    – user778806
    Commented Feb 5, 2021 at 13:18
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    You can set constraints on tasks in MS project at a task level, such that you can say "Start no earlier than {date}", but as I no longer have access to a copy of MS Project (having retired from work!) I can't recall exactly how to do that. This should, I believe, work in conjunction with dependencies so the dependency and the constraint will work together to give you the "Don't start until at least {date} AND Only start at least 20 days after the predecessor task" that I think may be what you are looking for.
    – Iain9688
    Commented Feb 5, 2021 at 14:38

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