=AND(B1="",A1+28<=TODAY())

or maybe

=AND(LEN(B1)=0,A1+28<=TODAY())

--

HTH

RP
(remove nothere from the email address if mailing direct)


"Jimbobn" wrote in message
...
My apologies I am somewhat of a novice to excel formulas

Would I therefore add the And funtion on the end of the date funtion ie:

Condition1

Formula is =A1+28<=Today() AND =B1=Null()


"SJ McAbney" wrote:

Use the AND() function in your Conditional Formatting expression.