# Roth Conversion Deadline: Dec. 31 and How Much to Convert

URL: https://elevatedtaxstrategies.com/tax-planning/roth-conversion-year-end-deadline/
Markdown: https://elevatedtaxstrategies.com/tax-planning/roth-conversion-year-end-deadline.md
Category: Tax Planning
Published: 2026-10-31
Author: Ramon Liriano Jr.

> A Roth conversion must happen by December 31, there is no April extension. Here is how to pick the amount that fills your bracket without overshooting.

## TLDR

A Roth conversion must be completed by **December 31** of the tax year. There is no April extension, unlike an IRA contribution. The amount you convert is added to your taxable income, to the extent the converted amount is otherwise untaxed. So one approach is to calculate how much room remains in your current **tax bracket**. Converting too much pushes the extra dollars into the next bracket. It can also trigger a higher **Medicare IRMAA surcharge** two years later. Once converted, the move cannot be undone. Since 2018, the law no longer lets you undo a Roth conversion.

Some retirement funding deadlines differ. You generally have until the unextended tax filing deadline to make a prior-year IRA or HSA contribution. This holds even if you extend your return. A **Roth conversion does not work that way**. It is a **calendar-year event**, full stop. Convert on December 30 and it counts for this year. Try to convert on January 2 and claim it for the year that just ended. That will not work. The IRS tracks the conversion by the date the funds actually move.

That hard stop is exactly why so many high earners miss the opportunity every year. The decision gets pushed into "I'll think about it before April." Then April arrives, and the window already closed back on December 31. A large conversion can raise your income enough to bring the 3.8% [Net Investment Income Tax](https://elevatedtaxstrategies.com/tax-planning/net-investment-income-tax-explained/) onto your investment income. Run the numbers before you convert, not after.

This guide covers three things. The deadline itself. How to figure out the right conversion amount without guessing. And the side effects that catch people off guard after the fact.

In this guide, you'll learn:

- Understand why a Roth conversion has **no extension**, unlike most other retirement moves
- Calculate how much room is left in your current **tax bracket** before converting
- See why converting is a **one-way door** since the 2018 repeal of recharacterization
- Recognize the **IRMAA surcharge** trap that shows up two years after a large conversion
- Know when a Roth conversion is the wrong move for your situation

## Why the December 31 deadline is absolute

A Roth conversion moves money from a traditional (pre-tax) retirement account into a Roth (after-tax) account. The money was never taxed going in. So the converted amount is added to your **taxable income** in the year the conversion happens. It gets taxed at your ordinary income rates.

**The IRS cares about the date the conversion transaction is completed.** It does not care about the date you decided to do it, or the date you filed your return. Unlike a traditional or Roth IRA contribution, a conversion has no such grace period. The IRS lets you make an IRA contribution up until the tax filing deadline. It still counts for the prior year. Conversions don't work that way. If the funds move in January, it is a conversion for that calendar year, no matter your intent.

**Practical cutoff: plan to initiate the conversion well before December 31**, not on the day itself. Processing a conversion can take a few business days, depending on the custodian. Especially one involving a sale of investments inside the account first. Say a conversion request is submitted on December 29 but does not actually settle until January 3. That counts for the following year, not the one you intended.

> **Heads up: Do not wait until the last week of December**
>
> Custodians get backed up with year-end requests. If you are converting from an employer plan rather than an IRA, the timeline can be even longer. Start the process by early December if you want certainty that it lands in the year you intend.

## How much to convert: filling the bracket, not guessing

The single biggest mistake in Roth conversion planning is picking a round number. Say "let's convert $50,000," with no check against your tax brackets first. The smarter approach is to work backward from the bracket structure itself.

### Step 1: Know your taxable income before the conversion

Start with your projected taxable income for the year, **before** adding any conversion amount. This includes wages, business income, interest, dividends, and any other income you already expect, minus your deductions.

### Step 2: Find the top of your current bracket

The 2026 brackets for a married couple filing jointly, for example, run through several marginal rates. The **22% bracket** tops out at **$211,400** of taxable income before the **24%** bracket begins. A single filer's 22% bracket tops out at **$105,700**.

**The "fill the bracket" strategy** means calculating a gap. Take the gap between your current projected taxable income and the top of the bracket you are comfortable paying. Then you convert exactly that amount, no more.

### Step 3: Worked example

A married couple filing jointly projects **$180,000** of taxable income for 2026, before any conversion. They want to stay inside the 22% bracket rather than spilling into 24%.

- Top of the 22% bracket (MFJ, 2026): **$211,400**
- Projected taxable income before conversion: **$180,000**
- Room remaining in the 22% bracket: $211,400 − $180,000 = **$31,400**

Check: $180,000 + $31,400 = $211,400. ✓

**Say the entire conversion is taxable and there are no other changes to taxable income. This couple can convert up to $31,400 and keep the conversion within the 22% bracket.** Convert a dollar more, and that next taxable dollar is in the **24%** bracket.

> **Note: Why some people intentionally cross into the next bracket**
>
> Filling only to the current bracket line is the conservative default. Some people intentionally convert further into the next bracket when they expect **future** rates to be even higher. For example, they may anticipate required minimum distributions large enough to push them into a higher bracket in retirement regardless. That is a longer-horizon judgment call, not a mechanical calculation, and depends heavily on your specific retirement income projection.

## The one-way door: no recharacterization since 2018

Before 2018, say you converted too much, or the market dropped right after you converted. You could **recharacterize**: essentially undo the conversion as if it never happened, by the extended due date of your return. **The Tax Cuts and Jobs Act eliminated this option for Roth conversions starting with the 2018 tax year.** It remains eliminated.

This means **once you convert, that income is locked in for the year**. Even if your account value drops the next week. There is no do-over. Run the numbers in October or November, then submit the request in early December.

**Roth conversion year-end window**

1. **Oct-Nov: Project your *full-year taxable income*.** Pull together wages, business income, and other known items. This is the number you compare against the bracket thresholds.
2. **Early Dec: *Calculate the conversion amount*.** Subtract your projected taxable income from the top of your target bracket. That gap is your conversion ceiling.
3. **Mid-Dec: *Submit the conversion request*.** Give the custodian time to process, especially if selling investments inside the account first.
4. **Dec 31: *Hard deadline*.** Funds must have moved by this date. No extension exists for a Roth conversion.

## The IRMAA trap: a surcharge that shows up two years later

Say you or your spouse are on Medicare, or will be within the next two years. A large Roth conversion can trigger an unwelcome surprise: a higher **Income-Related Monthly Adjustment Amount (IRMAA)**. That is the surcharge added to Medicare Part B and Part D premiums for higher-income beneficiaries.

**IRMAA generally looks back two years.** Your 2026 conversion affects your 2026 Modified Adjusted Gross Income (MAGI). The Social Security Administration would generally use that MAGI to set Medicare premiums for **2028**. It can use an older return when a newer one is unavailable, and can consider certain life-changing events. This two-year lag is exactly why people get blindsided. The conversion feels done and over with. Then a premium increase notice arrives two years later, seeming to come out of nowhere.

**The IRMAA brackets are indexed annually and change every year.** So we are not going to quote a specific 2028 dollar threshold here. The figure that applies to a 2026 conversion has not been published as of this writing. Check the current thresholds directly at **ssa.gov** or **medicare.gov**. Do this before finalizing a conversion amount, if you or your spouse are within two years of Medicare eligibility. **This is a scope-specific warning.** Say neither of you will be on Medicare for many years. Then IRMAA is not a near-term concern and should not drive the conversion decision.

## Who the "fill the bracket" math does not fit

Bracket-filling is the default framework, but it is not universal. A few situations where the standard approach needs adjusting:

- **You are near an IRMAA threshold within the next two years.** The income-tax savings from staying one bracket lower can be outweighed by a Medicare premium surcharge. Run both numbers before deciding.
- **You expect a much lower-income year very soon** (planned retirement, a business sale closing, a sabbatical). It may make sense to wait. Convert in that lower-income year instead of converting now at a higher marginal rate.
- **You will need the converted funds within five years.** Roth conversions carry their own five-year clock for penalty-free withdrawal of the converted principal if you are under 59½. Converting money you expect to need soon can create an unexpected early-withdrawal issue.
- **State tax treatment differs from federal.** Texas has no state income tax, so this is not a Texas-specific concern. Say you have recently moved from or to a state with its own income tax. Then confirm how that state treats the conversion for the year in question.

## How this fits with other year-end moves

A Roth conversion rarely happens in isolation. It is one lever among several when managing a high-income year. Others include retirement plan funding, charitable bunching, and timing of income and expenses. Our [broader guide for high earners reducing taxable income](https://elevatedtaxstrategies.com/tax-planning/reduce-taxable-income-high-earners/) covers the full menu of strategies beyond conversions.

Say you have not yet set up the account you would convert into. Our [backdoor Roth IRA guide](https://elevatedtaxstrategies.com/tax-planning/backdoor-roth-ira-step-by-step/) walks through the mechanics. It covers funding a Roth when your income is above the direct contribution limit. It also covers the pro-rata trap that catches people who still hold pre-tax IRA balances.

Working through this kind of year-end projection with clean, current books makes the bracket math far more reliable. That is part of what **ETS's** [tax planning advisory service](https://elevatedtaxstrategies.com/services/tax-planning-advisory/) is built around: running the actual numbers before December 31, not after.

## Common questions

### Can I convert part of my 401(k) directly, or does it need to go through an IRA first?

It depends on your plan. Some plans let you convert inside the 401(k). Others only let you roll money out when you leave the job or reach a set age. If you can roll out, you can often send it straight to a Roth IRA. If you owe a required minimum distribution this year, you must take it first. It cannot be converted. Check with your plan administrator on the timeline. In-plan conversions can also have their own processing lag before December 31.

### Do I have to pay the conversion tax from the converted funds?

You can, but it is generally better not to. Paying the tax from **outside funds**, like a savings or brokerage account, means the full converted amount keeps growing tax-free inside the Roth. Using the converted funds themselves to pay the tax can also trigger an early withdrawal penalty. That penalty hits the portion used for taxes. That is especially true if you are under 59½.

### Is there a limit on how much I can convert in a year?

No. Unlike annual Roth contribution limits, there is **no dollar cap** on how much you can convert in a single year. The only practical limit is how much tax you are willing to pay in that year. That is why the bracket-filling calculation matters so much.

### What happens if I convert and then the market drops right after?

The tax bill is based on the account's value at the time of conversion. Say the value drops afterward. You still owe tax on the higher converted amount, with no recharacterization available to undo it. Some people manage this risk a different way. They convert in smaller tranches throughout the year, not one lump sum in December.

### Does a Roth conversion count as earned income for Social Security purposes?

It is not earned income, so it does not touch the Social Security earnings limit. But it adds to your income. That can make more of your Social Security taxable and can reduce other breaks that depend on income. It does, however, count toward MAGI for IRMAA. It can also push your MAGI over the Net Investment Income Tax threshold. That holds if you also have net investment income. The conversion itself is generally not net investment income.

### I already filed my return for last year. Can I still do a conversion for that year?

No. Once the calendar year ends on December 31, the window for that year's conversion is permanently closed. There is no amended-return path to add a conversion after the fact. That is unlike a prior-year IRA contribution made before the filing deadline.

### Should I convert the same amount every year?

Not necessarily. Your conversion amount should reflect your **projected taxable income that specific year**. Say you have a sabbatical or a slow business year, with unusually low income. That is often a better year to convert more. A year with a one-time income spike is usually a year to convert less, or skip entirely.

## Ready to talk through your situation?

The right conversion amount depends on your full income picture for the year, not just one number in isolation. A free [Tax Discovery](https://elevatedtaxstrategies.com/discovery/) call, over Google Meet, no pitch, is a good way to run the bracket math together. Do it before the December 31 deadline. Free advice either way.