You could create a new Calculation field in your table that uses this as the calculation:
df = DateField ;
Year ( df ) + If ( Month ( df ) > 10 ; 1 ; 0 )
Substitute the name of your date field for DateField.
If you would prefer, you could use an AutoEnter calculation with the same formula [except change "df = DateField" to be "df = Get ( CurrentDate )"]. This assumes that you are always creating entries relevant to the current fiscal year.
If, however, entries are occasionally made outside of the current fiscal year (ie. a transaction entered on 11/1/2016 which should have been for 10/31/2016) then the Calculation formula I provided is a better option.
Their are several fiscal Year custom function definitions out there.
Check briandunning.com and fmfunctions.com
You will have to customize the calcs provided to adjust for your particular FY start and end dates.