I'm pretty sure Date::Manip will be able to help you out here, although it is quite a big module, it does pretty much anything date related you could ever want.

Normally i'd post another alternative, but Date::Manip pretty much does it all

Update Having just tried to put together some code to go with this magical hand waving, it turns out to be a little more tricky than i thought... mainly becasue some websites tell me that I can start my fiscial year whenever I want, and not in June, as I thought (which is the Australian Tax year) - although Date::Manip is still a good start.

f00li5h sits down to a nice meal of humble pie

Re: sort array by date by shonorio seems to be on the money.