Each month my expenses are due on different days, according to the corporate accounting calendar. I’ve tried to figure out a way to set that up so that it’s done for this year. So far I can only get it to do it each month at the time that the current one is due.
You cannot make a task due on 12 different days of the year if it does not follow a pattern (every four weeks, every four weeks on Saturday, etc.).
What I do in that situation for some of my financial reports is duplicate the task to 12 instances, and set the specific date needed with the repeat frequency to 1 year.
It means more tasks in a project (administrative or maintenance in my case), but it actually allows the most specific repeat options available and then you can customize the task title for each, i.e. “February Expense Report Due,” “March Expense Report Due.”