Paying Roth Conversion Tax: Outside Savings or IRA Withholding?

The short answer: The taxable part of a Roth conversion is added to your income for the year you convert. You can cover that tax with cash outside the IRA, with federal withholding taken from the IRA distribution, or with a mix. Outside cash lets the full amount you move reach the Roth, but only makes sense if that cash is not needed for your reserves. Withholding from the IRA is simpler, yet it shrinks the conversion, and if you are under age 59½ the withheld part may face the 10% additional tax unless an exception applies. Either way, tax is generally due during the year, not just when you file.

1. Three ways to cover the conversion tax

• Outside savings: you convert the full amount and pay the tax from a bank or taxable account, usually through estimated tax payments or extra withholding from wages or a pension.
• Withholding from the IRA distribution: the custodian sends part of the distribution to the IRS, and only the rest is deposited in the Roth. For nonperiodic IRA payments, IRS Publication 505 (2026) says federal tax is withheld at a flat 10% unless you choose a different rate on Form W-4R, anywhere from 0% to 100%.
• A mix: some withholding plus some outside cash, or extra withholding on a separate IRA distribution you were taking anyway, such as a required minimum distribution (which itself cannot be converted).

The 10% default is a withholding rate, not your tax rate. It can be too low or too high for your actual liability, so ask your CPA to estimate the total before choosing.

2. A hypothetical side-by-side

Hypothetical illustration only. Rounded numbers, a single assumed 22% federal rate applied to the whole amount for arithmetic, no state tax and no other income effects. It is not a 2026 bracket calculation, a projection or a client result.

• Option A, outside savings: $50,000 moves from the traditional IRA to the Roth IRA. About $11,000 of tax is paid from savings. The Roth receives $50,000, and savings are $11,000 lower.
• Option B, withholding: $50,000 leaves the traditional IRA, $11,000 is withheld for federal tax, and $39,000 is deposited in the Roth. Taxable income is still $50,000, because the withheld amount is a distribution that was not converted. If you are under 59½ and no exception applies, that $11,000 may also face the 10% additional tax (about $1,100 here).

Option A puts more dollars into tax-free Roth treatment, but it spends $11,000 of cash that may be your emergency reserve or money you would otherwise keep invested. Option B keeps your cash but moves less to the Roth. Neither is automatically better. The comparison depends on how long the money can stay invested, your tax rates now and later, and how much cash you need to keep on hand.

3. When outside savings may fit, and when it may not

It may fit when you have cash beyond your emergency reserve and near-term spending needs, you are unlikely to need the converted money soon, and paying from outside the IRA would not force a sale that creates its own tax.

Be cautious when the payment would drain reserves, when raising the cash means selling taxable investments with gains (which adds income of its own), or when you are relying on the same savings for a home, business or family need. In those cases a smaller conversion, or no conversion, may be the better choice. See when NOT to do a Roth conversion.

Withholding has costs too: a smaller Roth deposit, the possible 10% additional tax on the withheld part if you are under 59½, and a default rate that may not match what you actually owe.

4. Timing: the IRS expects tax during the year

Publication 590-A notes that if a conversion adds to your income, you may have to increase withholding or make estimated tax payments. Under Publication 505 (2026), you generally must pay estimated tax for 2026 if you expect to owe at least $1,000 after withholding and credits, and your withholding and credits will be less than the smaller of 90% of your 2026 tax or 100% of the tax shown on your 2025 return (110% if your 2025 AGI was more than $150,000, or $75,000 if married filing separately).

• 2026 estimated tax due dates: April 15, June 15 and September 15, 2026, and January 15, 2027.
• Withholding vs. estimated payments: Publication 505 generally counts withholding in equal parts across the four payment periods unless you choose to use the actual dates it was withheld. Estimated payments generally count when they are paid. That is why some people cover a late-year conversion with withholding rather than a late estimated payment. Confirm the effect with your CPA.
• Uneven income: if the conversion happens late in the year, the annualized income installment method in Publication 505 and the Form 2210 instructions may lower required earlier payments.

5. Side effects to check before you pay

Conversion income can raise the income used for Medicare Part B and Part D income-related surcharges (IRMAA), which generally look back two years, and it can change how much of your Social Security is taxed. Selling investments to raise the tax cash can add capital gains on top. For the Medicare piece, see Medicare and IRMAA. For the basics, see Roth conversion questions.

Questions to bring to your CPA

1. What is my estimated federal and state tax with no conversion, and with the conversion amount I am considering?
2. Should I cover it with outside cash, IRA withholding or both, and how much would actually reach the Roth each way?
3. Am I under 59½, and does any withheld amount risk the 10% additional tax?
4. Do I need estimated payments, extra withholding or the annualized income method to avoid an underpayment penalty?
5. Will raising the cash create capital gains, and does the extra income affect IRMAA or Social Security taxation?
6. After the conversion, what should I keep: confirmations, Forms 1099-R and 5498, and Form 8606 if required?

Start with a conversation, not a conversion order

Pinnacle Private Wealth coordinates Roth-planning questions with your existing CPA and other professionals. An introductory conversation can establish your goals, whether this planning fits your needs, and the scope and fees of a possible engagement. It is not authorization to move money. Please do not send tax returns, account numbers or sensitive documents through ordinary website forms.

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Serving Oswego and Aurora, IL, and virtually in all 50 states. Related: Roth conversion questions, when NOT to convert, RMD sequencing and tax strategy planning.

Official sources and review date

• IRS Publication 590-A (2025 edition; page last reviewed April 30, 2026): conversions are treated as rollovers; converted amounts are included in income; amounts kept rather than rolled over may be taxable and subject to the 10% additional tax; withholding or estimated payments may be needed.
• IRS Publication 590-B (2025 edition; page last reviewed April 30, 2026): IRA withholding, Form W-4R and the age 59½ early distribution rule.
• IRS Publication 505 (2026), Tax Withholding and Estimated Tax (page last reviewed April 30, 2026): the 10% default and W-4R choices for nonperiodic payments, the 90%/100%/110% rules, 2026 due dates, how withholding is counted, and the annualized income method.
• IRS Instructions for Form 2210: the underpayment penalty and treating withholding as paid evenly through the year.
• Social Security: Medicare premiums: income-related adjustments and the general two-year lookback.

Sources checked November 12, 2026. This guide discusses 2026 rules; future tax law, withholding rules and premium schedules can change. No tax bracket or premium threshold is assumed for a future year.

Educational information only, not individualized investment, tax or legal advice. The example above is hypothetical, and no savings or investment results are promised. Confirm your own situation with qualified professionals before acting. Pinnacle Private Wealth® is a marketing name used by Pinnacle Financial Planning, a Registered Investment Advisor. Registration does not imply a certain level of skill or training.

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