Do I need to make estimated tax payments after a Roth conversion in 2026?

Maybe, but not always. A Roth conversion creates taxable ordinary income, and whether you need quarterly estimated payments depends on how much tax the conversion adds and whether you are already covered by withholding or the IRS safe harbor rules.

Why conversions cause surprise tax bills:

Money moved from a traditional IRA to a Roth IRA is generally taxed in the year of conversion unless you are converting after-tax basis. No tax is withheld automatically unless you request it, so retirees often discover a large balance due when they file.

When you probably SHOULD pay estimated tax:

• The conversion is large enough that you expect to owe $1,000+ after withholding and credits
• You do not have wages or pension withholding to absorb the extra tax
• You are not covered by the safe harbor rules

Safe harbor rules that can protect you from penalties:

You usually avoid underpayment penalties if, through withholding and estimated payments, you pay the lesser of:

• 90% of your current-year total tax, or
• 100% of last year's total tax, or 110% if last year's AGI was over $150,000 ($75,000 MFS)

Planning options:

• Make an estimated payment for the quarter in which the conversion happens
• Increase withholding from wages, pension, or Social Security later in the year. Withholding is treated as if it was paid evenly throughout the year, which can be a cleaner fix than quarterly payments.
• Use the annualized income installment method on Form 2210 if the conversion happened late in the year and your income was uneven

Example:

If you convert $50,000 and your marginal federal bracket is 22%, that alone could add roughly $11,000 of federal income tax, before any state tax. If your withholding is already light, you may need an estimated payment.

Bottom line:

A Roth conversion does not automatically mean quarterly tax is due, but it often does for retirees and high savers with low withholding. Check the safe harbor before guessing.