A Roth conversion counts for 2026 only if the money actually moves before the year ends. The tax deadline in April does not help, because that date is for filing the return, not for doing the conversion. Once the money is in the Roth account, federal law gives no way to take the conversion back.
That combination catches people who treat a conversion like an IRA contribution, which can be made after New Year’s for the year before. A conversion has no such grace period. Anyone who wants one on the 2026 return has about nine weeks, and the bank or brokerage that holds the IRA sets its own pace for processing a request.
A Roth conversion moves money from a traditional IRA, SEP or SIMPLE IRA into a Roth IRA. The part that was never taxed becomes taxable income in the year of the move. A retiree weighing a conversion this fall is therefore deciding two things at once: how much to convert, and whether to be comfortable with that amount, because there is no reversing it later.
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Why the date is December 31
The IRS ties a conversion to the calendar year in which it happens. Its instructions for Form 8606, the form used to report a conversion, tell filers to complete Part II if they converted part or all of a traditional IRA to a Roth IRA during the tax year. The instructions for last year’s form refer to conversions made “in 2025.” The same wording applies to 2026 conversions on the return filed next spring.
The practical result is simple. A conversion finished on December 30 is a 2026 conversion. One that is still waiting on paperwork on January 2 is a 2027 conversion, taxed on the 2027 return and counted against 2027 income.
The reverse trap exists too. A retiree who expects a lower income next year might prefer the later date and wait on purpose. Whichever way the choice goes, the calendar date, not the filing date, decides which year the income lands in.
What “cannot be undone” means
Until 2018, a Roth conversion could be reversed. An owner who regretted one, perhaps after a market drop shrank the account, could recharacterize it back to a traditional IRA and cancel the tax. The Tax Cuts and Jobs Act ended that for conversions made after 2017.
The IRS’s Publication 590-B says a conversion of a traditional IRA to a Roth IRA, made in tax years beginning after December 31, 2017, “cannot be recharacterized as having been made to a traditional IRA.” The Form 8606 instructions repeat it: no recharacterizations of conversions made in 2018 or later.
The finality has a real cost. If the converted money loses value next month, the tax bill does not shrink with it. The tax is based on what was converted, and the Roth account starts with the lower balance.
Other Roth moves are not all final. The IRS’s FAQ page on IRAs says the tax-filing-date deadline still applies to recharacterizing regular contributions. Conversions are the exception, and the IRS says so plainly.
The tax that follows
The IRS says a conversion results in taxation of any untaxed amounts in the traditional IRA, and the amount is reported on Form 8606. A hypothetical makes the effect clear. A retiree who converts $20,000 of pretax money adds $20,000 to income for the year, on top of Social Security, pensions and other withdrawals.
That added income is taxed at ordinary rates. It can push part of the year’s income into a higher bracket, which is why many owners convert in pieces rather than all at once. The IRS pages do not set a recommended amount. The right number depends on the rest of the return, and a tax preparer can run it before the money moves.
Anyone paying the tax from outside savings keeps the full converted amount working inside the Roth. Anyone who takes the tax out of the IRA itself shrinks the amount that lands there. Both are choices the owner makes before the request, not after.
Required withdrawals come first
Owners who are old enough to face required minimum distributions, or RMDs, have another rule to respect. Publication 590-B says a required minimum distribution can never be rolled over. The minimum for the year cannot be converted to a Roth, so it has to come out in cash first, and the conversion can only use what remains.
The reward is on the other side. The IRS’s RMD FAQ page says required minimum distribution rules do not apply to Roth IRAs while the owner is alive. Money that is moved over stops generating future required withdrawals, though the beneficiaries of a Roth IRA do face them.
Timing a request is the final practical step. Custodians set their own cutoffs for conversion requests near year end, and a request that misses one slides into January. The safest approach is to ask the custodian for its cutoff date now and to work backward from it.
Is it too late to do a Roth conversion for this tax year?
It is not too late yet, but a conversion cannot be reversed, so a rushed one can cost real money in the wrong bracket. The mistake usually comes from converting a round number instead of the amount that fits the year’s room.
The Roth Conversion Window shows how to convert a piece of an IRA each year and stop at the line. It covers finding your window in the years before Social Security and RMDs, filling the bracket and stopping at the line, and the Medicare line two years ahead, and it includes a room finder and a multi-year planner worksheet.
Get the Roth Conversion Window guide with the Medicare line two years ahead →
This article was produced with AI assistance and edited for accuracy against the sources linked above.
