Thanks DMarkM1 for following up on this. I decided to not use Turbo Tax for my filing as I could not get around several problems and I needed to file early. But after I got your reply I opened up Turbo Tax and tried the entries for form 2555 again. I noticed Turbo Tax did a program update as it came up and the layout of the data entry screen for the physical presence residence is now different. I had no problem leaving the field blank (just as I did not have a problem the first time around). The original problem I had was error messages regarding the business days field when I came to efile. I tried to replicate this to see if the problem was still occurring but I could not as now Turbo Tax is saying I cannot efile for some other reason. So, I do not know if my original problem is fixed or not. The bottom line though is that the software needs to be changed so that the number of business days field accepts zero - this is a perfectly valid value for this field.
