I funded Roth IRA for 2024 and 2025 by mistake. I backed out excess contribution before deadline 2024 so no penalty, but when do i pay tax on resultant income 2024/25?

before tax filing date including extension: positive earnings allocable to the excess are included in income on 1040 Line 4b for the year of the contribution. negative earnings are ignored; in any case, for purposes of basis, consider the original contribution amount as returned.

--

If any positive earnings were not reported on the filed return, you need to amend 2024 tax return.

@deedso57 

For contributions that were made for tax year 2024, the attributable earnings are reported on your 2024 tax return, even if you made the contribution or withdrew the earnings in 2025.  Enter the income on your 2024 tax return by going to the retirement income section, entering a 1099-R, say you need to create a substitute 1099-R.  Enter the total amount of the withdrawal in box 1, the taxable attributed earnings in box 2a, and use codes P and J in box 7.

For contributions that were made for tax year 2025, the attributable earnings are reported on your 2025 tax return.  You will get a 1099-R next January.