You Probably Need to Re-Run Your Roth Conversion Math

For about eight years, the Roth conversion conversation had a built-in alarm clock. The lower tax brackets from the 2017 tax law were scheduled to sunset at the end of 2025, and a whole cottage industry of advice grew up around it: convert now, while rates are low, before the window slams shut. It was good advice. It was also urgent, deadline-driven, and a little bit anxious.

Then the One Big Beautiful Bill Act passed in 2025 and made those brackets permanent under current law. No more automatic 2026 tax-bracket cliff. That sounds like good news, and mostly it is, but it also means that almost everything you may have internalized about Roth conversion timing was built for a world that no longer exists. If you ran the numbers a couple of years ago, or worse, if you absorbed the urgency without ever running them, the strategy deserves a fresh audit. Here are five things the new law changed, framed as five questions worth asking before you convert another dollar.

1. The Deadline You Were Planning Around Just Vanished

The headline change is the simplest. The 10%, 12%, 22%, 24%, 32%, 35%, and 37% brackets are no longer scheduled to expire after 2025. The "convert before 2026" pressure is gone.

This is more than a footnote, because urgency can make us do things we wouldn’t otherwise consider. A deadline pushes you to convert a large chunk in a single year to "beat the sunset," which can shove that income up into a higher bracket and cost you more than spreading it out ever would have. With the brackets fixed in place, you can now model a conversion strategy several years out with real confidence, filling up the lower brackets a slice at a time without a countdown clock forcing your hand.

There is a good bit of wisdom literature to be quoted here. So much of foolish money behavior is just impatience. A permanent bracket structure is an invitation to be diligent instead of hasty, to plan several years ahead without dread or panic.

2. No Sunset Means No Excuse to Rush a One-Way Door

A Roth conversion is a one-way door. Since 2018 you have not been able to recharacterize or reverse a conversion once it's done. If you convert $50,000 and then have a surprise income event that bumps you into a higher bracket, you cannot reverse the conversion to fix it and lower your taxable income back down to pre-conversion levels.

That matters more now because the deadline pressure is gone. Under the old sunset rules, you could at least understand the argument: convert now, accept some risk, and beat the closing window.

But if the window is staying open, patience becomes part of the strategy. Before you convert, model the ripple effects first. What does this conversion do to your bracket? Your deductions? The other thresholds we're about to discuss? Measure twice, convert once. This is exactly the kind of mostly-irreversible decision where a little modeling on the front end protects you from a year of regret on the back end.

3. Accidentally Erasing The Senior Deduction

We’ll need actual numbers. Grab your pencils.

OBBBA created a temporary senior deduction for taxpayers age 65 and older:

• Up to $6,000 single / $12,000 MFJ (subject to qualifications)
• Available from 2025 through 2028
• Begins phasing out when MAGI hits $75,000 single / $150,000 MFJ
• Phases out by 6 cents for every $1 above the threshold
• Fully gone at $175,000 single / $350,000 MFJ when both spouses are 65+ ($250,000 MFJ if only one spouse qualifies)

Now the math.

A married couple over 65 has $145,000 of MAGI before any Roth conversion. They are under the $150,000 phaseout line, so they still qualify for the full $12,000 deduction.

Then they convert $50,000.

Their MAGI moves from $145,000 to $195,000. That puts them $45,000 over the phaseout threshold.

$45,000 × 6% = $2,700.

So the conversion did not just create $50,000 of taxable income. It also erased $2,700 of deduction.

If they are in the 22% bracket, the visible tax cost is:

$50,000 × 22% = $11,000.

But the deduction clawback adds:

$2,700 × 22% = $594.

So the real federal cost is closer to $11,594 before considering state tax, IRMAA, Social Security taxation, marketplace subsidies, or anything else MAGI touches.

On its own, the clawback isn't a reason to rule out a conversion. But it’s another layer that needs to be factored in.

The better question is:

"If I add this much income, what else changes?"

Same thing with the new SALT rules. The cap increased to $40,000, which may help households in high-tax states. But that benefit phases down once MAGI passes $500,000 and is back to the old $10,000 floor by $600,000, so a large conversion can erode the very benefit it is meant to capture. Again, the issue is the chain reaction more than the bracket. Besides, if your income exceeds $500,000, you’re already in an extremely high tax bracket making the tax math of a Roth conversion that much less likely to work in your favor.

4. Pairing Your Conversion With Your Giving

For families that prioritize charitable and generous giving, the new law has opened a genuinely useful door. Beginning in 2026, charitable giving and conversion income can be paired with more intention.

There's a new 0.5%-of-AGI floor on charitable deductions that now affects itemizers, meaning the first slice of your giving no longer generates a deduction. That sounds like a discouragement, and on its own it is. But it also strengthens the case for "bunching," concentrating several years of planned giving into a single year, often through a donor-advised fund, so you clear the floor and itemize meaningfully in that year. Now layer a Roth conversion onto that same year. The conversion creates taxable income; the bunched gift creates a deduction to absorb part of it. Done thoughtfully, you convert and you give in a coordinated move rather than treating them as two unrelated line items.

In short, if charitable giving is already part of your plan, consider whether bunching gifts into a donor-advised fund in the same year as a Roth conversion could help offset part of the tax cost. The point is not to give just for the deduction. The point is to coordinate what you already intend to give with the year your taxable income is intentionally higher.

5. The MAGI Ripple Effects

A conversion raises your MAGI, and a raised MAGI can ripple outward in ways that don't show up on your bracket worksheet. For anyone near Medicare age, IRMAA, the income-related surcharge on Medicare premiums, works on a two-year lookback, so a conversion today can raise your premiums two years from now. A conversion can also increase how much of your Social Security gets taxed, and for those buying coverage through the marketplace, it can shrink a health-insurance subsidy. None of these automatically kill the case for converting. They're reasons to consider whether now is the right year and to know the full price tag before you do, rather than discovering it on a statement next year.

What to Actually Do This Week

Talk to your financial or tax advisor. If your Roth strategy was built around the old sunset, it was solving a problem that no longer exists. Ask them "how much should I convert, in which years, given everything my MAGI is connected to?"

That's a planning conversation that likely needs to happen again. And it's exactly the kind of decision that rewards counting the cost before you start to build.

Want some help thinking this through? I did too. That's part of why I started Openhanded Wealth — to walk with folks like you through decisions that feel complicated, but don't have to stay that way. If you've got questions, reach out. I'm a real person, and I won't pressure you into buying products you don't need. You don't have to navigate this alone. [Email Me] or [Schedule a Call]

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