Form or software to help calculations for current year's Roth conversions?
I'm not talking about modelling whether you need Roth conversion. I mean specific calculations if, e.g., you're maxxing the 24% tax bracket this year and you want to hit its AGI spot on. Is there a form or tool built to help estimate exactly how much you should convert, relative to the rest of your income etc.
For anyone new to this, the problem is that you don't have all the W2s and other year-end summaries like you did before retirement. You have to estimate all these values and do all your actual converting before the end of the calendar year ... you can't wait until April 15. Some values are pretty straightforward but others aren't, and there can be quite a few wrinkles.
I have tried using last year's tax form, but you can't do calculations or keep extensive running notes right inside a Form 1040. I've also tried Excel, but for me it turns into running "stream of consciousness" calculations over the course of a given year, especially since I pick it up at least twice each year (some conversions at beginning of year, and the finish the rest near the end). Last year I used over 300 rows in Excel, sigh.
There's lots to consider:
- Calculate how much conversion "room" you have between e.g. 24% bracket ceiling and predictable values like Social Security income, IRS Standard Deduction, pension, etc.
- Plug in estimated dividends or interest income (before the end of the year).
- If you sell stock to pay for conversion taxes - possibly incurring NIIT - track that, because it decreases conversion capacity.
- Keep in mind IRMAA cliffs, if you have more than just Medicare A. (Actually I don't, so I don't need this. But most people do.)
- If you do some conversion early in year (stocks usually lower) and some later in year, track the amounts so you still hit the bracket total just right.
I'm not sure there really can be any software or tool that can do all this. But I'm sure there are some that can help, or at least help point out some things you might miss.
FWIW for tax year 2025 I was ~$11k low; I could've converted that much more. I was being a little careful and leaving some extra wiggle room to not go over but, in the future, I figure it's better to just try to hit it spot on, and it's okay to be slightly over. (A.k.a. I'd rather be a few thousand into 32% territory than 11k under the 24% ceiling. Fortunately, I don't have to worry about IRMAA.)
Thanks if you can help!