Yes, Claimable can distinguish between calendar days and working days in your region when automatically setting task due dates.

For instance, if you choose to use working days, for a task with a due date that is to be set 5 working days after the claim creation, Claimable will calculate the 5 days, excluding weekends and local public holidays in your country/region.

To ensure the correct public holidays are determined, just set the "Public Holidays Region" option under Account Settings.