I am using conditional formatting in excel to highlight dates in a
spreadsheet column that are 28 days old from the current date.

I am usning the formula =A1+28<=Today() which works fine.

I now want to be able to check the condition of a second field before the
first date field is highlighted as overdue.

ie if cell A1 date is greater than or equal to 28 days and cell B1 is empty
then highlight cell A1

Any ideas anyone?