Dan, I had the same issue. We are not the only ones though: https://community.atlassian.com/t5/Jira-Service-Management/Preview-of-importing-holidays-using-ics-in-SLA-calendars/m-p/2168593

I created a calendar with our companies time off for holidays defined in outlook 365.  Saved it with full details.  When i try to import it I can an error - We can't use that file format try importing your holidays using an ICS file.  Do you have a supported method of creating the file that will be in the format you are looking for. 

Product Update - 20th December

Hi everyone, 

This feature is now being rolled out. Here's the link to the documentation. Thank you for all your feedback. 

If you are looking for being able to reuse holidays across calendars, make sure to vote on the JAC ticket for that feature.

@Manas Shukla

That would be very nice to have! When do you think that will be in place ?

Would it take more time for you guys to add something region-based that would automatically update those events each year in the background ?

On project side, we would have like a check list for the calendars: Check United States and check Canada, and that would add every known holidays updated in the backend of Jira Cloud. (option to manually remove each items if the business doesn't apply this)

If I go further, based on Agents location in their profile, that would only apply Region Specific Holidays to specific agents (on their SLAs)

Even on location field in tickets (SLA would pause)

Product Update - 20th October

Hi everyone, 

Here's a preview of how we are thinking about this feature. Please leave your feedback in the community post.

Please provide this feature to Cloud

Please add this ability to Cloud! 

this is almost 10th fault after we migrated to cloud. Now I can see it is a big mistake. Whole cloud junk is a one big issue. TIme to look elsewhere I think

Would also be nice to have (in SLA Calendar)I

• the possibility to define the time (not onlye the date) in the  SLA-Calendar, becaus we have annualy repeating half-day-holidays (e.g. 24th of December, so the Holiday should be  24.12.21 12:00 - 24:00, anualy)
• Exception-Date-Time, e.g. we have a Maintenance - window every 2 to 3 weeks, so the service time ends at this dates 2h earlier (e.g. Wednesday Servicetime is from 7:00 to 16:00 instead of 7:00 to 18:00)

As part of this we should also be able to share calendars across projects.  We have one project per customer and doing every holiday for every customer is an extremely time consuming exercise!