How to update Contact record Last Updated When Removing and updating tags

We are working through the API to apply tags and remove tags to an existing contact record. We have a Higher Logic integration where they pull updates about a contact record based on the last_updated field on the Contact record. When I remove a tag from a contact through the API, how can I also update the Contact record’s last_updated date so that HL can pick up our tag changes?

You don’t have any way to directly affect the last updated field. However, at this point, a tag application now counts as an update to the contact. Otherwise, you can create a custom field that you merely modify to trigger the system to set the last updated field.