how to create finanicial year like 0910???

Question

i have a field project number. now

i have also 15 fields but in project number field i wanted to add 2 data from earlier field.

in one field there is listbox and there is 3 items.

when every item will be selected then in project number it must be add that record and also add financial year.

like 0910

this is depending on 31-03-2009 to 01-04-2010 then it will show 0910.

now when i add from list box then i should add in last of financial year in incremented mode on selecting of every listbox item 01

this is look like

ET/BHEL/091001

ET/BHEL/091002

ET/BHEL/091003

and 

ST/BHEL/091001

ST/BHEL/091002

ST/BHEL/091003

here ET and ST is that listbox item and BHEL is project_id ..

my database is ms-access....