The tax treaty between India and the US says
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- An individual who visits a Contracting State for a period not exceeding two years for the purpose of teaching or engaging in research at a university, college or other recognized educational institution in that State, and who was immediately before that visit a resident of the other Contracting State, shall be exempted from tax by the first-mentioned Contracting State on any remuneration for such teaching or research for a period not exceeding two years from the date he first visits that State for such purpose.
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This is a good deal for a teacher from India visits the US to teach as their income will be free from both US tax (by the above treaty) and India tax (as India does not tax its non-residents). But a US teacher visiting India would pay no India tax, but they would still pay US tax because US taxes its citizens no matter where they live. Would they also be able to use form 2555 to exclude income from US taxation?