Larry,

If I understand correctly, your fiscal year starts Oct.01? So now it is
FY511?

Are you entering PO's manually through a form? If yes, then it's just a
question of a VBA function to calculate the next "number"; use the
function in the form control's Default Value property, and it will fdo
the job. Now, the function:

Function Next_PO_No() As String
Dim vThisMonth As Integer
Dim vFM As String
Dim vFY As String
Dim vLast As String
Dim vPrefix As String
vThisMonth = Month(Date)
Select Case vThisMonth
Case 1 To 9
    vFY = Right(Year(Date), 1)
    vFM = Format(vThisMonth + 3, "00")
Case 10 To 12
    vFY = Right(Year(Date) + 1, 1)
    vFM = Format(vThisMonth - 9, "00")
End Select
vPrefix = "PO-FY" & vFY & vFM & "-"
vLast = DMax("PONumber", "tblPurchaseOrders", _
    "Left([PONumber],9)='" & vPrefix & "'")
Next_PO_No = vPrefix & Format(Val(Right(vLast, 3)) + 1, "000")
End Function

HTH,
Nikos

Larry

Just an observation...

If your field contains something like "OCT 2006 - PO-FY601-001" from your
post, your table structure might benefit from a bit more normalization.  It
appears you have multiple facts embedded in a single field.

If so, you would need to either "parse out" information (e.g., Fiscal Year)
to use it, or would have to redundantly store a field of "Fiscal Year" data
to use it (e.g., show all POs from FY 06).

One of the early steps in normalization can be paraphrased as "one field,
one fact".  You could store your combined facts in separate fields, and use
a query to concatenate them together into the string you provided as an
example "PO#".

Regards

Jeff Boyce
<Access MVP>