My wife works at the UN and we both have G4 visas. Her income is non taxable whilst my income is taxable. Can I file as married filing jointly, and just not declare her non taxable income or must I declare her income as non taxable? Or are there additional forms?

Actually, you CAN file jointly. I had a similar issue with a married couple who works for the United Nations, and they showed me a UN advisory packet that cited the IRC that allows tou to file jointly while NOT claiming your spouses income.

Your wife should be able to get the same information from her work.

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