so just add once you figure out what is smaller (110% of 2024 vs. 90% of 2025) if you haven't paid Q1/2 ES for that amount, you will have some penalty but only for a few months if you get those caught up the penalty will stop accruing. By Q3 ES Sep deadline you need to have paid 75% of the annual ES total, 100% by Q4 in Jan.
AI method helps if you have uneven income and associated tax payment especially later in the year like a Roth Conversion. If your income was even thru the year (or front-loaded), but you missed estimated tax payments earlier in the year, the AI method will not eliminate those penalties as it will still show you underpaid in Q1 etc.
