Ok, for the majority of your fiscal year calculations, you will be best off properly defining the fiscal year of your date field, or at least duplicating the date field, and defining the FY on this:
But what if you just need to adjust the month for FY calcs such as calculating the number of months that have passed in the current FY, this calculation should come in handy:
Min(Iif(Month(Today()) > 3, Month(Today()) - 8, Month(Today()) + 8))
The above is set to the UK FY of April to March, and just remember to switch the two 8’s to their new numbers