=EOMONTH(A1,0)+45
Format as Date

Or, if you don't have Analysis Toolpak installed,

=DATE(YEAR(A1),MONTH(A1)+1,0)+45

--
Kind regards,

Niek Otten

"Midas NDT Sales" wrote in message
...
Hi,

Can anyone suggest the answer to a simple problem, I want excel to
calculate
a nett date on an invoice.

If I put a date in for example 16/12/2005 I want the sheet to return a
date
that is 45 days following the end of the month. Effectively the
spreadsheet
must jump to the end of the month and add 45 days to it. Hence the result
will be the same if you enter 06/12/2005.

Any help would be greatly appreciated.