One of the standard questions on the Form 433A is: Have you lived out of the country for more than six months in the last 10 years? Why does the IRS ask this?
Reason: Under Internal Revenue Manual 5.1.19.3.7 residing outside the US for any continuous absence of six month or more suspends the Statute of Limitations for the time period outside of the country. This could potentially extend the Statute of Limitation for a long time.