Trigger formula field update with automation

[johnch]

Hello, looking for help on how to trigger the update of formula field when a record reaches a condition. My example is the following: I have a "Birth Date" field which contains the birthdate as Date. I have a formula field which calculates the current year "Anniversary Date": 

DATETIME_PARSE(YEAR(NOW())&"-"&DATETIME_FORMAT({Birth Date},'MM-DD')).

How can I trigger the update of this "Anniversary Date" when the record reaches the day after the anniversary?

[TheTimeSavingCo · Accepted solution]

`IS_AFTER()` is what you're looking for I think, along with a `DATEADD() to add one day to the anniversary date so that it's the day after the anniversary