Just some thoughts on this core part to get you going:
.. say the bill ran from 13/01/08 - 13/03/08 i would need 1 part
to calculate the unit over that period so 18 days of jan 28 feb 13 mar**

To partition it as desired under the correct month/yr col based on start/end
dates, try this sample from my archives:
http://www.freefilehosting.net/download/3e4i0
Apportioning days within a date range under correct month cols.xls

**Think it should rightly be: 19 days under Jan08, 29 days under Feb08,
13 days under Mar08 based on 13/01/08 - 13/03/08 (inclusive)

P/s: Stick to only 1 clear question per post, make it attractive for
responders.
--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
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