When is a tax that is based on income not an income tax? When are treaty provisions that provide for relief from double taxation properly ignored? The answer in the U.S. is when the tax is the Net Investment Income Tax, generally referred to as N.I.I.T. In the Toulouse case, the U.S. Tax Court refused to allow a U.S. citizen resident abroad to claim a foreign tax credit when it came to the N.I.I.T. In addition to the technical issue, the case is interesting because it illustrates the choice of procedures to be followed when challenging an I.R.S. increase in tax for reasons unrelated to the computation of income or the availability of a credit. One is the Collection Appeals Program (“C.A.P.”) and the other is the Collection Due Process program (“C.D.P.”). Here, the taxpayer chose the C.D.P., as it allowed the taxpayer an opportunity to challenge an adverse position of the I.R.S. by filing a petition in the U.S. Tax Court. Andreas Apostolides and Wooyoung Lee explain the rationale of the court in denying double tax relief. In particular, it points out that taxpayers who seek treaty relief in matters other than withholding tax rates do so at their peril.