Thank you dmerz,
Yes, IRA/SEP/SIMPLE checkbox is checked on the tax form.
So, my answer to the TT' s question "Where is this distribution From?",
since it is from not a pension rollover or anything but just individual account at Vanguard ,
TT has automatically checked "No2. Other IRA distribution", I just leave it at that, right?
Very confusing, TT doesn't give explanations for "Other distribution" option...
