Sure...if you use the Desktop software every year. After preparing the current year's data in the normal software, you can then use the What-If worksheet where you can transfer the current year's $$, into a second column for predicting the next year's situation...then change all the values for each of the next year's $$ categories to see what the tax hit ends up being for the additional amounts you want to convert, remove W-2 income, and can also check a box to use the next year's expected tax rates.
Issues?
1) IF the 401k is a traditional pre-tax 401k, then most, or all of the $$ transferred to ROTH IRA will add to your other income (pension?) which bumps up your AGI and taxable income ....so it may not all be at the lowest tax rate...the actual % tax bracket will then depend total taxable income (after deductions)...and even that will vary too depending on what your filing status is (MFJ, or single?)
2) You are not taking SS yet, but if you are also getting a pension to live on, and have started making Medicare payments too, if your income is too high for any one year (including those 401k-to-Roth conversions), then you could get hit with higher Medicare part B and D premiums the next year. How much, again depends on whether you are single or married.....so pre-planning and dividing up the conversions over several years is usually preferable.
You can see the Medicare IRMAA tables here:
2023 Medicare Parts A & B Premiums and Deductibles 2023 Medicare Part D Income-Related Monthly Adjus...
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To get the What IF worksheet, after you fully fill in the current year's taxes in the desktop software, you need to switch to Forms Mode to be able to search for and open the What If worksheet. Then work on that in Forms mode to plan and see the effect of varying the next year's 401k-to-Roth IRA conversion amounts.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
