Hi, today I am going to clarify one important thing which bothers a lot of of my Blog readers. I will go step by step through example and explain them.

First I’m going to build simple Project:

Now I will create three Resources:

and I will assign them to Tasks:

I will now make **Task 1 **as 25% completed:

**Task 2** actually __starts earlier__ than planned (that is, earlier than its **current Start Date)**. So Task 2 ** Actual Start Date** is manually updated to an earlier date.

In ** the Mark on Trask -> Update Tasks dialog box** I will enter

__25% Complete__,

__the earlier Actual Start Date__for Task and click OK:

and:

and I will get:

Now, I will put status date to 24.07.2018, and then I will update the project to reschedule uncompleted tasks to after **the Status Date**:

and:

and I will get:

**The Actual Start Dates** of Task 1 and Task 2 are __not changed__, but their **Finish Dates** are __changed__ for the later dates. That is OK! Why? Start date is not changed because some work is **already done **and it was started at those Start Dates, so they cannot be moved or changed. What is done is DONE! It is written in the stone!

And now, where my blog readers have the biggest problem? Look at this.

I will make **Task 2** 100% complete based on its earlier **Actual Start Date** and **original Duration**, so I will enter** the Actual Finish Date** in the Update Tasks dialog box:

Finally, I will get:

the question is: **The Duration** for this task is shown only **0.75 days** instead of its scheduled **Duration** of **3 days?**

At the first look, it seems that this is a bug, because Start Date id 24.07.2018, finish Date is 26.07.2018, but Duration is 0,5 days instead of 3 days. But this is not a bug. I will explain why this is totally normal result:

- First I put 25% Completed for the Task 2 which had 3 days Duration. It means that actual Duration is 25% of 3 days is 0,75 days
- Then I moved the all unfinished Tasks after the status date, which is 24.07.2018.
- Because Task 2 has Finish to start relationship with Task 1, and Task 1 was supposed to finish at 27.07.2018, and the remaining part of Task 2 is supposed to start at that date (27.07.2018)
- BUT! I put 100% at %Complete, and Finish date to 26.07.2018. which is
**before**Task 1 was finished. - This means that Task 2 has no work left, so it was needed only 25% of original estimated work, and this is 0,75 days and 6 hours! If you have expected that those 2 days (25.07.2018, and 26.07.2018) work will be performed, you were wrong and this is because nothing is supposed to be done at that dates because Task 1 was not finished at that time. So the earliest date on which work on Task 2 is supposed to be done is 27.07.2018, and this is before the finish date of Task 1 which is 26.07.2018

Hope this helps.

Regards!