Other financial discussions

How or where do I go to amend my return?

i just got off the phone with the IRS and they stated that i checked off where it says : Standard Deduction someone can claim : Your spouse as a deduction which means I get no stimulus payment. I file married file separate and never had this confusion of a question. I filed back on April 15 exactly and was wondering why no stimulus. I want to amend and can I. How do I go about this? Please help