Refund Status

Turbo Tax indicated my federal return was electronically transmitted and accepted 10/26/2020. My estimated refund date was shown to be 11/16/2020. However, on 11/20/2020, the IRS.gov, check refund status site, says, "We cannot provide any information about your refund".  As of 11/20/2020, no federal refund was deposited into my bank account. The state refund was deposited on 11/7/2020.

      1. Is it possible:

               a) Turbo Tax Premier did not filed or misfiled my federal return?, or

               b) My federal return and/or my federal refund was lost?

      2. When should 1(a) or 1(b) be a concern and what should I do at that point?