I don't know of a simple Access function but I do have this code that might work for you:
Add it to an Access Module:
Public Function WorkingDays(dDate As Date, lInterval As Long) As Date
Dim x As Long ' Count of Working Days
Dim y As Long ' Count of actual Days
Dim dNewDate As Date ' The date being checked
Do Until x = lInterval
dNewDate = DateAdd("w", y + 1, dDate)
'1 = Sunday
'2 = Monday
'3 = Tuesday
'4 = Wednesday
'5 = Thursday
'6 = Friday
'7 = Saturday
If Weekday(dNewDate) > vbSunday And Weekday(dNewDate) < vbSaturday Then 'Using the Default of Sunday as firstday of week
'if dNewDate <> a holiday then (do your check here against your holiday table
x = x + 1
'End if
End If
y = y + 1
Loop
WorkingDays = DateAdd("w", y, dDate)
End Function
to call it just set it as the value of a field.
Me.[DeliveryDate] = WorkingDays([ShipDate],5)
if [ShipDate] = 1/5/00 then [DeliveryDate] will be five workdays from now or 1/12/00
Hope this helps