=SUMPRODUCT(--(TODAY()-A2:A300<31),B2:B300)
where column A holds your dates and column B holds the amount and by
"spreadsheets' date" you men todays date

"KJo" wrote in message
...
I need a formula that calculates the amount ($) in one column based on the
date that coincides with the amount (another column) and also 30 days less
than the spreadsheets' date. How would I begin to write that? Help... and
thanks!