I expect to make around $2,400 in interest income this year. I messed up my taxes for 2025 because I had myself set as married after a separation and ended up having to pay the IRS underpayment penalty.
How can I avoid this underpayment penalty for 2026 and pay taxes on the interest income?
I have already called my brokerage firm and asked if they will withhold taxes on the interest income and they said they don't do that.