Roth conversions · Social Security
Should you do Roth conversions before or after claiming Social Security?
By Jim Swiech, CPA · Updated
Quick answer
Before, in most cases. Once Social Security starts, every dollar you convert can pull up to 85 cents of benefit into taxable income with it, so the same conversion costs more. In our example, a married couple drawing $40,000 a year from an IRA pays $12,360 of federal tax on a $100,000 conversion before benefits and $18,013 on the identical conversion once they collect $48,000 of Social Security.
That is $5,653 more for the same $100,000. About $17,800 of Social Security became taxable, $3,696 of the senior deduction phased out, and the combination pushed far more of the conversion into the 22% bracket.
Why the same conversion costs more after benefits start
Social Security is taxed on a sliding scale. The IRS adds up your other income plus half your benefit and calls it provisional income. For a married couple, up to half the benefit becomes taxable once that figure passes $32,000, and up to 85% of it once it passes $44,000. Those lines were set in 1983 and 1993 and have never been indexed, so a normal retirement income lands on top of them. A Roth conversion is other income. Convert $100,000 and you do not just add $100,000 to the return; you also drag the benefit through the 85% zone on the way.
| Conversion | Before Social Security (age 63) | Rate | After Social Security (age 68) | Rate |
|---|---|---|---|---|
| $25,000 | $2,660 | 10.6% | $4,950 | 19.8% |
| $50,000 | $5,660 | 11.3% | $7,950 | 15.9% |
| $100,000 | $12,360 | 12.4% | $18,013 | 18.0% |
| $150,000 | $23,360 | 15.6% | $30,333 | 20.2% |
Look at the smallest row. Before benefits, a $25,000 conversion sits entirely in the 10% and 12% brackets. After benefits, that same $25,000 carries a real rate of 19.8%, higher than the rate on $100,000, because the first dollars converted are the ones that push the benefit into the taxable zone. That is the tax torpedo, and it hits small conversions hardest.
The years that do the work
The cheapest conversion years are the ones with the least on the return: after the paycheck stops and before the benefit starts. If you retire at 62 and claim at 67, that is five years. If you delay the benefit to 70, it is eight, and the benefit itself grows 8% for each year past full retirement age. Delaying Social Security and converting in the gap are two halves of one plan: the delay creates the low-income years, and the conversions use them.
When converting after benefits still makes sense
Sometimes the gap has already closed and you are collecting. That does not end the conversation. Once provisional income is high enough that 85% of the benefit is already taxable, the torpedo has done its damage and additional conversions are taxed at the bracket rate, plus whatever the senior deduction phase-out and the Medicare line add. In the table above, that is why the rate on $100,000 after benefits is lower than the rate on $25,000. If required minimum distributions are coming at 73, or 75 if you were born in 1960 or later, and will land you in the 22% or 24% bracket anyway, converting at a similar rate now, with the benefit on the return, can still beat waiting. The test is the rate on the last dollar converted this year against the rate the IRA will face later. The calculator on the Roth conversion page shows both.
What to check before you decide
Three things. First, whether the conversion crosses the Medicare income line that applies two years out, because that surcharge lands on both spouses. Second, whether you have already filed for benefits: a withdrawal of the application is allowed once, within twelve months of entitlement, and every benefit dollar received must be repaid, while past full retirement age you can instead suspend the benefit until 70, which takes it off the return and earns the delayed credit. Third, the survivor picture: a conversion done while filing jointly is taxed at joint rates, and the same conversion done later by a widow or widower filing single is not.
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Quick answers
- Should you do Roth conversions before or after claiming Social Security?
- Before, in most cases. Once benefits start, each converted dollar can pull up to 85 cents of Social Security into taxable income with it. In the example on this page, a married couple drawing $40,000 from an IRA pays $12,360 of federal tax on a $100,000 conversion before benefits and $18,013 on the identical conversion once $48,000 of Social Security is on the return. The $5,653 difference comes from $17,800 of benefit the conversion made taxable, $3,696 of senior deduction it phased out, and far more of the conversion landing in the 22% bracket.
- Why does a small conversion cost a higher rate than a large one after Social Security starts?
- Because the first dollars converted are the ones that push the benefit through the taxation zone. For the example couple at 68, a $25,000 conversion carries a real rate of 19.8% while a $100,000 conversion carries 18.0%. Once 85% of the benefit is already taxable, additional conversions are taxed at the bracket rate plus whatever the senior deduction phase-out and the Medicare line add.
- Does delaying Social Security help with Roth conversions?
- Yes, twice. Delaying creates benefit-free years in which conversions are cheaper, and the benefit itself grows 8% for each year past full retirement age up to 70. Converting in the gap and claiming later are two halves of one plan.
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.