So - is your fiscal year the same as the actual year? I know some companies - their FY may start the beginning of June or some such.
I'd use default values for this - they'll update when ever the form is opened - but if the formula is right, they won't change until the year changes - for example, substring(today(), 1, 4) would always be the current year. substring(today(), 1, 4) + 1 would always be next year. Does that make sense?