It would be nice to input formulas and or be less restrictive in the Filter function. I am trying to filter out anniversaries and birthdays by the current month so that I can send out mailers. Right now, I have to create a separate column with a function that pulls out the month and then I have to go into filter and change the filter to the respective month each month. It would be nice to just put a filter of "is…MONTH(TODAY()) and it would automatically update each month as well as I would be able to avoid having to create a separate column to accomplish this task.
You’re already halfway there with your formula field. Use this formula (tweaked to match your field names):
MONTH(Birthday) = MONTH(TODAY())
That will return a 1 or 0. Change your filter to only show records where that formula returns a 1. Each time you open that view, it will recalculate
TODAY(), which will refresh the filter.