I am going to build a project with several tasks and subtasks that have the same structure. For example:

  2. task 1
  3. task 2
  4. task 3
  6. task 1
  7. task 2
  8. task 3
  9. .......

What I would like to do is to place a formula in the "predecessor" field that would be something like "([actualID-1]FS+5days)" so that if I copy this formula on task 2 and task 3 line they will always refer to task 1 and task 2. In this way I can have hundreds of sections but only one formula to create the dependencies from the predecessors.

Is it a thing that can be done maybe with some custom field/column? Thanks

  • Do all of your tasks need the 5 day lag? If not, you can select Task 1, Task 2, Task 3 and click the Link task button. It will set 1 as the predecessor to 2, 2 as the predecessor to 3 and so on. If you need a 5 day lag after every task - why?
    – JulieS
    Commented Mar 4, 2017 at 16:17
  • my actual section is composed by 5 subtasks and the relationship is the following: task1: task 1 task2: task1FS+10 days task3: task2SS+5 days task4: task3+5 days task5: task3FS+10 days I dont know if it's clear enough. If not please ask :)
    – Brian748
    Commented Mar 6, 2017 at 15:56
  • From your new comment, it doesn't appear to have any real pattern. As Tom notes, you cannot write formulas for task relationships. You can collapse a summary task copy/paste and maintain the same relationships in the newly pasted tasks.
    – JulieS
    Commented Mar 9, 2017 at 16:55

1 Answer 1


No, MSP doesn't permit formula-based predecessor relationships. There are two obvious ways to get what you want:

  1. After creating your hierarchical task list in MSP, copy-paste the relevant table (containing predecessors field) to Excel. Use text formulas to manipulate the predecessors field in Excel, then copy-paste back to MSP. As long as the predecessors are correctly formatted, MSP will then modify the schedule logic to match.
  2. Use vba (i.e. macro) code to directly modify the predecessors string in MSP.
  • I will try to make an Excel file as you suggest... this could be a nice trick!!
    – Brian748
    Commented Mar 6, 2017 at 15:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.