@Kipmc7 to avoid interest penalties you have to either pay 110% of last year's liability or 90% of this year's liaiblity. Given some of the complexities of lumpy income (which the Roth conversions can create), the only way of really knowing is completing Form 2210, which is a doozy.
Best to simply pay the estimate by January 15. (The Sept 15 payment deadline is for income through August only).
https://directpay.irs.gov/directpay/payment?execution=e1s1
Since you are taking the income to the top of the 24% tax bracket, that means your AGI should be $195,950.
If you are not aware and are receiving Medicare, your income will cause a one year increase in your Medicare premiums in 2025 for something called IRMAA. So the $164.90 monthly premium would be approx $428 per month for that one year only.
If your AGI exceeds $199,000 for 2023 (using an estimated 3% inflation rate), the IRMAA premium would jump to appprox. $528 per month during 2025, so you may want to reduce the Roth conversion by a few dollars to ensure you are below this thresshold. Even going over the thresshold by $1.00 will increase your IRMAA premiums to the nexst tranche. Read the link below.
if you won't be on Medicare in 2025, then don't worry about this.
https://thefinancebuff.com/medicare-irmaa-income-brackets.html
