I dunno, I only read the last few posts before mine, and I just like arguing (especially with Tommy!), so.... Here's a real kicker about the USC surcharge: it also applies to income from employments outside the state, because these are taxed as Schedule D Case III rather than Schedule E. A relative of mine was working through a Norwegian payroll in their oil industry in a well paid job (150k - 180k), whilst also being tax resident here. He'd already paid hefty deductions in Norway, and you would think that he had no further liabilities here under the DTA... however, he was hit for USC on the whole lot, including the 3% on the amount over 100k. I think that would most likely fall foul of EU treaty principle freedom of movement of workers, as I don't see how he could be taxed at a higher rate for being employed abroad than here. Not sure if it would apply to Norway (EEA but not EU), but would surely apply to EU.