Yes, you need to amend your 2022 tax return.
The amount reported with code 8 on the Form 1099-R form the 401(k) was not eligible for rollover to the IRA, so that amount now constitutes an excess contribution to the IRA. Assuming that you filed your 2022 tax return or requested a filing extension by April 18 2023, you have until October 16, 2023 to obtain a return of excess contribution (not a regular distribution) from the IRA to avoid having to report an excess-contribution penalty on Form 5329 that would otherwise have to be included with your amended 2022 tax return. Your amended 2022 tax return will also need to include an explanation of the investment gain or loss that must accompany the returned IRA contribution. If there is a gain, the gain must be included on the 2022 tax if the rollover occurred in 2022. If the rollover occurred in 2023, the gain will go on your 2023 tax return instead.
