Sorry, I answered too quickly.
If you want to store the year back in the table...
1. Set up the table with an [EventDate] and set its format to mmm/dd/yyyy. Also a [YearDate] with a format as yyyy
2. In your input form, both the [EventDate] and [YearDate] fields will have their corresponding fields in the table as their source, and set their format to the same as it is in the table. The important one is the yyyy in the [YearDate]
3. In the AfterUpdate event of the [EventDate] put this code Me.YearDate = Me.EventDate
That should do it.
Tom