SQL/VBA: How to group by a fiscal year starting from a day other than 1st day of month

Question

I’m trying (using MS Access) to group some data by a fiscal year, which can be different to the calendar year.

If every fiscal year always started on the 1st of a given

Answer 1

This is actually quite simple, and you don't need any additional table or fields.

The method is to offset the financial dates to match the calendar year. For example:

FinancialYearFirstMonth = 9
FinancialYearFirstDay = 2 

First, toalign to primo of the month:

DateMonth = DateAdd("d", 1 - FinancialYearFirstDay, SomeDate)

Next, expand to also align to primo of the year:

DateYearMonth = DateAdd("m", 1 - FinancialYearFirstMonth, DateAdd("d", 1 - FinancialYearFirstDay, SomeDate))

If the financial year is not lagging but leading the calendar year, add 12 months:

DateYearMonth = DateAdd("m", 1 - FinancialYearFirstMonth + 12, DateAdd("d", 1 - FinancialYearFirstDay, SomeDate))

Now you can have the financial year and month and (with some limitations for the ultimo date(s) of a month) day using the normal functions:

FinancialYear = Year(DateYearMonth)
FinancialMonth = Month(DateYearMonth)
FinancialDay = Day(DateYearMonth)

Of course, month names will not fit. If these are needed, use MonthName of the original date.