Use the fixed-date or contact date property workflow types to center a workflow around a date. Read more here.
When you create your fixed-date or contact date property workflow, you will be able to center your workflow around a calendar date or a date property. When setting this up, you will see a check box labeled Recur annually. If that box is checked, the workflow will ignore the year set in the specified property/date and operate off the current year.
If the recur annually box is not checked, then the workflow will use the full date/property, including the year.
If you have a contact date property workflow with the recur annually box unchecked and a contact has a property date value of Dec 6, 2011, the action cannot be scheduled because that date is in the past.
However, if the recur annually check box is checked, the workflow will execute the action on the month and day specified, ignoring the year in the property. You'll see in the example below that the action is scheduled for Dec 6 of the current year (2017).