Excess Roth contribution in 2024 - how to apply the excess to my 2025 contribution

Hello,

I accidentally contributed an excess of $1000 to my Roth IRA in 2024. I've already filed my taxes for 2024. I would like to apply the excess to my 2025 Roth contribution amount. I've read that I need to pay 6% on the excess and complete/file form 5329. But I am not clear how and when I do that.

Do I complete form 5329 and pay the 6% somehow on my 2024 taxes (that have already been filed), or do I wait and complete the form and pay the 6% when I submit my 2025 taxes? Either way, I think the form that needs to filed is the 2024 5329? If I just roll it over into the 2025 Roth amount, it seems that I don't need to report any interest earned? And I just need to pay the 6% once, correct?

Bonus question - is my IRA custodian involved in this matter, or do I just track this myself and make sure I only contribute $6,000 for 2025?

thank you!

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