I am sorry for your mother's passing. If her SSA-1099 was her only source of income, then it would likely not be taxable and a final tax return would not be required under her SSN for the time period up to her passing. See below for reference.
An estate tax return would be required if the estate had earnings of $600 or more for the year. If one is required, you would file it under the EIN for the estate. See IRS link below for reference.
https://ttlc.intuit.com/questions/1899144-is-my-social-security-income-taxable
https://www.irs.gov/businesses/small-businesses-self-employed/deceased-taxpayers-filing-the-estate-i...
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
