Currently, I sum up resource invoices by the following statement:
=IF($B14<$B13,IF($AK13="yes",SUMIF(B$2:$B13,$B13, $BK$2:BK13),$BL13),"")

B = resource, AK = invoice is for this year, BK =invoice $, BL = default
value if no invoice $.

This formula works great - EXCEPT at year end cleanup when I need to remove
all the old rows no longer required for reporting. For each line I remove,
the line about gets a REF# error.

How can I get around this?