Year for medieval accounts e.g from agrarian estates ran from Michaelmas 
to Michaelmas (29 Sept)- not sure when this went out of use.

David Legare wrote:
> To confuse matters further, the federal fiscal year
> (Oct. - Sep.)is related to the old Celtic year that
> began on Samhain (Holloween).  I have no idea why this
> is.
>  
> --