=if(and(A2="",B2=""),0,B2-A2+1)

or use OR as Frank suggested:

=if(OR(A2="",B2=""),0,B2-A2+1)



--
Regards,
Tom Ogilvy


"Katherine" wrote in message
...
The add one will not work because it will add one to those
persons who have no payment coming - I have to have a way
to identify that the one is added only to those that have
earned payment --