Buybacks

So I last certified in 2024 to get on the SAVE plan.

This used 2023 income data

When I hit 120 months and can do a buy back (May 2029) will the buy back calculation be based on my 2023 income since that was the income certification that was “active” during 2024 - 2026?

Or will they pull my taxes for 2024 and calculate the Aug - Dec 2024 buy back on that income? And then pull my 2025 income and base my Jan 2025 - Dec 2025 buy back on that income? And then repeat for 2026.

How does it work?