I have a solution where the user inputs data during certain times of the year. Does anyone know how I can make a field unmodifyiable after a certain date?

In field format uncheck the "allow entry into fieldXX" (the filed you do not want anyone to modify) this will not allow someone to enter data. then define that same fieldXX as a button and assign a script to it.

ie

if date < date fieldYY

goto fieldXX

this will put you into the field for editing as long as the date field condition is met

Stu