Roth conversions · Brackets
How do you fill the 12% bracket with a Roth conversion?
By Jim Swiech, CPA · Updated
Quick answer
Convert the difference between the top of the 12% bracket and your taxable income before the conversion. In 2026 the 12% bracket runs from $24,800 to $100,800 of taxable income for a married couple and from $12,400 to $50,400 for a single filer.
A married couple drawing $40,000 from an IRA and nothing else has $7,800 of taxable income after the standard deduction, so a $93,000 conversion fills the bracket to the dollar. It costs $10,820 of federal tax, a real rate of 11.6%.
Why 12% is the bracket worth filling
The jump from 12% to 22% is the biggest step in the federal rate schedule. Apart from the eight-point jump from 24% to 32% far up the schedule, every other step is two or three points; this one is ten. Money converted at 12% and left to grow tax-free is money that would often otherwise come out of the IRA at 22% or 24% as a required minimum distribution, or at single-filer rates for a surviving spouse. Filling the 12% bracket is the cheapest conversion most retirees will ever do, as long as the other lines on this page stay clear, and the window in which you can do it is usually the years between the last paycheck and Social Security.
The 2026 lines
| Bracket | Married filing jointly | Single |
|---|---|---|
| 10% | $0 to $24,800 | $0 to $12,400 |
| 12% | $24,800 to $100,800 | $12,400 to $50,400 |
| 22% | $100,800 to $211,400 | $50,400 to $105,700 |
The standard deduction sits on top of these: $32,200 for a couple and $16,100 for a single filer, plus $1,650 per spouse or $2,050 single once you are 65. So a couple both 65 or older can have adjusted gross income well above $100,800 and still be inside the 12% bracket.
The worked example, line by line
Married couple, both 63, retired, drawing $40,000 a year from a traditional IRA. No pension, no Social Security yet, no other income. Taxable income before the conversion is $40,000 less the $32,200 standard deduction, which is $7,800. The 12% bracket ends at $100,800. The room is $100,800 minus $7,800, or $93,000.
| Conversion | Federal tax | Real rate | Last dollar taxed at |
|---|---|---|---|
| $93,000 (fills the bracket) | $10,820 | 11.6% | 12% |
| $100,000 (spills $7,000 into 22%) | $12,360 | 12.4% | 22% |
The first row is the answer. The second shows what happens when you round up: the extra $7,000 is taxed at 22% instead of 12%, which is not a disaster, but it is the exact cost of not doing the subtraction. The real rate on the $93,000 conversion is below 12% because some of the converted dollars land in the 10% bracket first.
Three things that change the room
Social Security. If you are collecting, the conversion raises the taxable part of your benefit, and that taxable benefit uses up bracket room too. The subtraction still works, but the number you subtract is larger and moves as you convert. The calculator on the Roth conversion page handles that loop. Capital gains. Long-term gains and qualified dividends stack on top of ordinary income and are taxed at 0% up to $98,900 of taxable income for a couple in 2026. A conversion that fills the 12% bracket pushes those gains out of the 0% band and into 15%, which is a real cost that does not show up in the bracket table. Health insurance. If you are under 65 and buy coverage through the marketplace, the premium tax credit has its own income line, and a conversion that fills the 12% bracket can shrink or eliminate the credit for the year. Check that line first; for many couples in their early sixties it is the most expensive line on the return.
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Quick answers
- How do you fill the 12% bracket with a Roth conversion?
- Convert the difference between the top of the 12% bracket and your taxable income before the conversion. In 2026 the bracket ends at $100,800 of taxable income for a married couple and $50,400 for a single filer. A couple drawing $40,000 from an IRA has $7,800 of taxable income after the standard deduction, so a $93,000 conversion fills the bracket exactly and costs $10,820 of federal tax, a real rate of 11.6%.
- What happens if the conversion goes over the top of the 12% bracket?
- The extra dollars are taxed at 22%. For the example couple, rounding a $93,000 conversion up to $100,000 puts $7,000 into the 22% bracket and raises the cost to $12,360. Not a disaster, but it is the exact price of skipping the subtraction.
- Does filling the 12% bracket affect capital gains?
- It can. Long-term gains and qualified dividends are taxed at 0% up to $98,900 of taxable income for a couple in 2026 and stack on top of ordinary income. A conversion that fills the 12% bracket pushes those gains out of the 0% band into 15%, a cost that does not appear in the bracket table.
Updated . Reviewed by Jim Swiech, CPA.
Educational and general in nature. Not tax, legal or investment advice, and not a recommendation to convert. Figures are 2026 federal amounts under the assumptions stated on this page; your return has more lines than any example. Go Beyond Tax is a brand of Swiech Consulting LLC.