Update: I just got off the phone with the IRS. The agent said that my mom could file with itemized deductions (as another had posted above). If my stepfather's 2022 filing is itemized, then no action would be taken. If his filing is standard, the IRS would send a letter to the filing party to say that the standard deduction would be zero or that his filing could be amended to itemize. The agent pointed to Publication 501, page 7, Special Rule #11. Thank you all. I learned a lot today!
