Did you report the March 2024 distribution on your 2023 tax return, even though you did not have a 1099-R for it? You weren't supposed to do that. You report an IRA distribution in the year that you actually take it, even if it's a late distribution for the prior year. Schwab is reporting it correctly. Your 1099-R for 2024 is supposed to include all distributions that you took in 2024. There is nothing for them to correct.
You will have to file an amended return for 2023 to remove the distribution that you reported in 2023 but actually took in 2024. You make the correction on your 2023 amended return, not on your 2024 tax return.
This answer has been verified for accuracy by an Intuit expert employee
