@ChickenBurger
Because you made the regular withdrawal in 2024, and not 2025, it did not have the opportunity to "clear out" the excess contribution. Look at form 5329 from your 2024 return, line 24. If that shows an amount, that is the amount of excess that is being carried into 2025. You need to make a regular withdrawal in 2025, before December 31, of the amount shown as excess Roth contribution on your 2024 form 5329 at line 24. That regular withdrawal will count as a removal of the excess that was carried forward. It should not be taxable, unless you are under age 59-1/2 AND the withdrawal cuts into conversions that are less than 5 years old.
Then, you can separately, still do a "backdoor" conversion in 2025 via the normal method.
Yes, you can do a backdoor conversion of more than one year's contributions at a time. For example, on January 15, 2026, you contribute $7000 designated for 2025. Then on January 20, you contribute $7500 designated for 2026. Then on January 25, you convert $14,500. That will work fine. Just be aware that the non-deductible 2025 contribution will be reported on your 2025 return, but the non-deductible 2026 contribution and the 2026 conversion won't be reported until your 2026 tax return filed in the Spring of 2027.
