This standalone download contains the most recent holiday definitions for Outlook.
The download title specifically mentions Outlook 2007 and Outlook 2010 (as they contain this exact same hol-file) but you’ll find it also works with Outlook 2003, Outlook 2013 and Outlook 2016 (msi).
This download can’t be used with Microsoft 365 and Click-to-Run installations of Office but these versions already have the latest holiday definition file applied (currently up to 2026).
For details about how to use this hol-file see: Holiday updates for the Outlook Calendar.
Things to note
While this is the latest standalone hol-file published by Microsoft, it is getting outdated.
Although this definition file is available in various languages and contains holidays for 88 countries up to the year 2028, many only go up to 2020.
Outlook 2013 contains holidays up to 2022 and Outlook 2016, 2019 and Microsoft 365 up to 2026.
Installing the latest updates for Outlook may contain a more up-to-date hol-file as well. How to get these updated definitions into your Calendar is discussed in: Holiday updates for the Outlook Calendar.
The guide mentioned above also provides a standalone hol-file with all holidays up to 2026 (similar to Microsoft 365) that can be used with Outlook 2003, Outlook 2007, Outlook 2010, Outlook 2013 and Outlook 2016 (MSI) as well.