Determine start date based on given end date

[Felix van Dijk]

I would like to create a start date off of a given "End Date". 

In the workflow a user would create an Issue and provide a End Date for the project. This date is their desired end date by which the implementation. I want to take this end date and add 180 days in front of it to determine the start date. 

[John Funk · Accepted solution]

Hi Felix - Welcome to the Atlassian Community!

Create an automation rule based on an Issue Created trigger. 

Add any Conditions needed so that it only fires for the issues you want to set the Start date for. 

Then add an action for Edit Issue. Select the Start Date field. 

In the empty box for by the Start Date put this: {{issue.End Date.minusDays(180)}}

where the End Date is the EXACT name of your field. 

[Felix van Dijk]

Perfect. Thank you

[Bill Sheboy]

Hi @Felix van Dijk 

Yes, and...to John's suggestion:

You may want to consider adding a condition to test if the "End Date" minus the 180d is in the past (before the current date).  That may prevent mistakes / errors in process.

Kind regards,
Bill

[Felix van Dijk · Accepted solution]

I solved this with the following process: 

To create an automation rule in Jira that calculates the estimated start date by subtracting 180 days from an End date, follow these steps:

Access Jira Automation:

Go to your Jira project.
Click on Project settings.
Select Automation from the sidebar.
Create a New Rule:

Click on Create rule.
Set the Trigger:

Choose a trigger that suits your workflow, for example, Issue Created or Issue Updated.
If you want this rule to run when an issue is created, select Issue Created.
If you want this rule to run when an issue is updated (e.g., when the End date is set or changed), select Issue Updated.
Add a Condition (Optional):

If needed, add a condition to ensure the rule only runs when the End date is present. For example, add a Issue fields condition to check if the End date is not empty.
Add the Action to Edit the Issue:

Click on New action.
Select Edit issue.
Set the Estimated Start Date:

In the Fields to Set section, choose the field where you want to store the calculated start date (make sure you have a custom field for this, like "Estimated Start Date").

Use the following smart value to calculate the date:

json
Copy code
{{issue.End date.minusDays(180)}}
Here’s a step-by-step guide to set this up:

Click on Choose fields to set....
Select your custom field for the start date (e.g., "Estimated Start Date").
In the field for the start date, enter the smart value {{issue.End date.minusDays(180)}}.
Review and Save:

Review your automation rule.
Give your rule a name (e.g., "Calculate Estimated Start Date").
Turn on the rule.