If you are a non-US person who happens to spend a lot of time in the United States you are secure in the fact that you will not become liable for US taxes on your worldwide income so long as you do not spend 183 days or more in the United States during any tax year; RIGHT?
WRONG! To avoid a very dangerous pitfall you must be careful to read all of the fine print in the rules that determine US tax residency for non-US persons.

