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The “Inactivate” Button on MS Project – What is it for?

Meet the author:

Tal Levanon – Founder and partner in “Tal Levanon – HCP Ltd”, an expert project scheduling consultant and creator of the Hidden Critical Paths (HCP).


The “Inactivate” button is located on the “Tasks” toolbar in the “Schedule” section of MS Project.

When executing a project, there are often tasks that we did not think of – additional to the scope of the project and sometimes tasks that we planned are canceled.


Do we cancel the canceled tasks with the “Inactivate” button?

The short answer is: No. More precisely: Not at all.

To understand why, let’s review what the button really does:



The best way to explain it is through an example. Following is a mini project of 5 tasks. The project begins on August 15th and ends after 6 work days:

If we want to cancel Task C, we will mark the task and press “Inactivate”.

The button, assumedly, canceled the task.

Why ‘assumedly’? After all, Task C is marked as canceled, its graphic configuration changed into a box with a small line and it is empty, its following link changed colors and the project duration went from 6 work days to 5. So why ‘assumedly’?

The reason is: MS Project “deletes” the task duration, but does not change its logical links. In other words: the button does not delete all of the information related to the task itself, but rather keeps it in the task and its linked tasks.

When a certain task is marked as canceled, the links are assumedly canceled too. But the tasks dependencies of the tasks linked to it – both predecessors and successors – remain unchanged – and that is not something you can see, especially not on schedule with dozens, hundreds and thousands of tasks.

In our mini project:


The solution provided by MS Project, deleting the task duration and retaining the links, is a certain interpretation for the concept of ‘Task Cancellation’.


There is another option where canceling a task means deleting the task entirely. In this case – Task A will not have a successor (which is incorrect) and Task E will not have a predecessor. This will lead to a situation where Task E begins on the first day of the project:

It is impossible to decide which of the interpretations is right. The option offered by MS Project will be right for some projects and deletion might be appropriate in others, and there will be projects in which deletion is necessary, but the predecessor for Task E will not be Task A, but rather Task B, and perhaps a new Task, Task F, which will come before E.


When tasks have SS (start-to-start) or FF (finish-to-finish) links with delays – the results may be very complex and illogical.


Let’s take our mini project again, with a slight change – Task C is linked to Task E with a finish-to-finish dependency + 2 days:

Now, let’s “cancel” Task C with the “Inactive” button:

Did we really intend for Task E to end with Task A or should it end three days after “A”? And perhaps, (logically) it is not linked to A, but rather to B once we cancel the scope of work? And can it really start before A and B finish?


The Project definition for the “Inactivate” button says that this option was created in order to examine the addition and removal of task from the project and its impact on the project itself. The button’s original name is “Active/Inactive” – best explaining the aim of the button.


For original Project documents, press here


This option is mainly used to examine adding and removing a task before execution or in claims, when one wants to determine how a delay impacts the schedule, for example with Time Impact Analysis (TIA).


To fully answer that question, the different cases must be separated (there might be more situations – feel free to write me and I will respond):


  1. The project is yours, for you and there’s no need to report to anyone on what happened and why.
  2. A project with a basic schedule where you must report every change to the project and analyze what caused the changes.
  3. Examining project execution alternatives.
  4. Schedule analysis for a claim.


Case #1 – The project is yours, for you and there’s no need to report to anyone on what happened and why


In this case, I recommend deleting the task. If there’s no need to retain history, why keep rows of irrelevant tasks? After deletion, to ensure that there are no problems or, alternately, to detect faults in advance and handle them – run HCP-Go on the schedule. In addition, you can make sure that the paths that you think are critical and hidden critical are the same paths that the Gantt chart “thinks” are critical and hidden critical.


Case #2 – A project with a basic schedule where you must report every change to the project and analyze what caused the changes


In this case, you definitely must not delete the canceled tasks. There are two reasons for that:

  • א. When you are required to investigate and compare what happened and why – the canceled tasks should be listed, just to prove that they existed and were canceled.
  • ב. Interesting fact – in large-scale projects, based on my experience, canceled tasks have a way of coming back to life and reappearing in the project. That’s an excellent reason not to delete

Therefore, if we do not delete tasks, but we don’t want it to impact the project, we must do the following:

  1. Reset the task duration.
  2. Make sure that all predecessors and successors have FS (finish-start) links only and that there are no delays.
    Or (based on the project) Delete the links and verify that you retain all of the links required for the predecessor and successor tasks.
  3. Add a note in ‘Notes’ field with the date, description and reason for the change.


Case #3 – Examining project execution alternatives

This is what the button was meant to do. Be sure to create correct links to predecessors and successors for each alternative. For example, the mini project below, providing two execution alternatives:


Use the “Inactivate” button to cancel Option 2 and see what happens to Option 1:

Use the “Inactive” button to restore Option 2 and cancel Option 1.

Case #4 – Schedule analysis for a claim

We sometimes want to prove that delays were caused by one of the parties. In this situation, we can use the basic schedule and add all of the delays that were caused by the said factor. Using the “Inactivate” button, we can see how each delay impacted the project and how all delays impacted the project.

It is important to note that, as stated above, the links are a very important factor in the process and its outcomes – so this has to be done very carefully, while paying close attention to the details and applying meticulous control.

You received a schedule (Gantt chart)
with hundreds of activities.
Do you want to know what happens inside,
and if there are problems, where are they?

If you answered 'YES' - then we have a solution for you!

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