BZ, I have another quick question

In the Substantial test, the formula is 1/6 year2003 days + 1/3 year2004 days + year2005 days. But if someone wasn't here in 2003 and 2004, but was here in 2005 for more than 183 days, that is still okay right? In this case, the first two numbers would be 0. I looked through the chart in Pub519 and didn't see anything say that Year-1 and Year-2 cannot be zero.

But if I'm right, why would IRS come up with a formula like this?

Thanks a lot!