“Render to Caesar the things that are Caesar’s, and to God the things that are God’s.” (Matthew 22:21, ESV)
Most of the retirees I sit down with think of their working years as the season for financial strategy, and retirement as the season to coast. In one important way, it's the opposite. The years right after you stop working, but before Required Minimum Distributions force your hand, are often the single best tax planning window you'll ever have. I call it the gap—and if you let it pass by without a plan, it's usually gone for good.
If you have a meaningful balance in a traditional IRA or old 401(k), this window is worth understanding before you drift into it by accident.
Quick answer: The Roth conversion gap is the stretch between when you retire and when RMDs begin (age 73 or 75, depending on your birth year). Because taxable income often drops sharply in these years, it's usually the cheapest window you'll ever have to convert pre-tax IRA money to a Roth IRA—by converting just enough each year to "fill up" your current tax bracket without spilling into the next one.
What Is the Roth Conversion Gap?
The gap is the stretch of years between when your paycheck stops and when the IRS requires you to start withdrawing from your pre-tax retirement accounts. Right now, RMDs begin at 73 if you were born between 1951 and 1959, and at 75 if you were born in 1960 or later. If you retire at 62 or 63, that can leave you a decade or more where you control exactly how much taxable income shows up on your return.
A Roth conversion is simply moving money from a traditional, pre-tax IRA into a Roth IRA. You pay ordinary income tax on the amount you convert, up front, and after that the money grows tax-free and comes out tax-free in retirement—including for whoever eventually inherits it. The question isn't whether you'll pay tax on that pre-tax money eventually. You will, one way or another. The question is what tax bracket you'll be in when you do.
Why This Window Is So Valuable
During your working years, your income is usually at its highest, which often means your tax bracket is too. Once you retire and before Social Security and RMDs begin, many retirees see their taxable income drop sharply—sometimes down to just interest, dividends, and modest withdrawals to cover living expenses. For a few years, you may find yourself sitting in the 10 or 12 percent bracket for the first time in decades.
That's not a coincidence to waste. It's an opportunity to convert pre-tax dollars into Roth dollars while the tax cost of doing so is unusually low, rather than waiting until RMDs force large, mandatory withdrawals on top of Social Security income, likely pushing you into a higher bracket for the rest of your life.
How Bracket-Filling Works
The strategy isn't to convert everything at once—that would likely push you into a much higher bracket in a single year and defeat the purpose. Instead, we look at how much room you have left in your current tax bracket and convert just enough to "fill it up" without spilling into the next one.
Say a retired couple has $40,000 of taxable income after deductions in a given year, and the 12 percent bracket for their filing status extends up to $96,950. They have roughly $57,000 of room left in that bracket. Converting $57,000 from a traditional IRA to a Roth IRA this year means that entire conversion is taxed at 12 percent, rather than the 22 or 24 percent it might be taxed at once RMDs and Social Security are both layered on top of each other in a few years.
Repeat that most years during the gap, and a retiree can move a meaningful share of a large IRA into Roth dollars at a fraction of the tax cost they'd otherwise pay later, all without ever leaving the lower brackets they're already sitting in. Financial planning researcher Michael Kitces has written extensively on this approach, which he refers to as systematic partial Roth conversions to fill the lower tax bracket buckets—the same bracket-filling logic described here, laid out in more technical detail for advisors.
The Cost of Doing Nothing
Skipping this window doesn't make the tax bill disappear. It usually makes it larger. Left alone, a traditional IRA keeps growing, and once RMDs begin, you're required to withdraw a percentage of the balance every year—whether you need the income or not. Layer that mandatory withdrawal on top of Social Security, and it's common for retirees to find themselves in a higher bracket at 75 than they were at 65, simply because nothing was done during the gap years.
The scale of what's at stake is easy to underestimate. For a retiree with a substantial IRA—say $1.5 million or more—left untouched to keep compounding for a decade or two before RMDs force it out at higher rates, the gap between converting strategically and doing nothing can run into the hundreds of thousands of dollars over a lifetime, once RMDs, Social Security taxation, and Medicare surcharges are all stacked on top of each other. Every situation is different, but for larger balances this isn't a rounding error—it's often one of the biggest financial decisions of retirement.
There's a second cost that's easy to overlook: the survivor's tax bracket. When one spouse passes away, the surviving spouse moves to filing as a single taxpayer, often with roughly the same income but narrower tax brackets and a smaller standard deduction. Converting during the gap years, while both spouses are alive and filing jointly, can meaningfully reduce the tax bill the surviving spouse faces for the rest of their life.
What to Watch Out For
A Roth conversion strategy done well is powerful. Done carelessly, it can create problems of its own. A few things worth planning around:
Pay the tax from savings, not the IRA. If you withhold the conversion tax from the IRA itself, you shrink the amount that actually reaches your Roth and lose out on future tax-free growth on those dollars. Whenever possible, pay the tax bill from a savings or brokerage account outside the IRA.
Watch Medicare's IRMAA surcharge. If you're 63 or older, a large conversion can raise your Medicare Part B and Part D premiums two years later, because IRMAA is based on your tax return from two years prior. A big, one-time conversion in the wrong year can trigger a surcharge that lasts a full year even though your income has since returned to normal.
Mind Social Security's tax torpedo. If you've already started Social Security, a conversion adds to your provisional income and can cause a larger share of your benefit to become taxable, effectively raising your marginal rate on the conversion beyond the bracket you think you're in. This is one reason the years before you file for Social Security are often the cleanest window for converting.
Know the five-year rule—actually, the two five-year rules. Each Roth conversion has its own five-year clock before the converted amount can be withdrawn penalty-free if you're under 59½, though this rarely affects retirees already past that age. Separately, if this is your very first Roth account, the account itself needs to be open five years before earnings can be withdrawn completely tax-free. Kitces has a clear breakdown of the two five-year rules for Roth IRA contributions and conversions if you want the full technical picture. It's a detail worth tracking, not a reason to avoid converting.
Don't forget state taxes. Some states tax retirement account withdrawals and conversions just like the IRS does; others don't tax retirement income at all. Where you live, or plan to retire to, changes the math.
Stewardship, Not Just Strategy
It's worth saying plainly: none of this is about outsmarting the IRS or chasing every last dollar. It's about being a faithful steward of what's already been entrusted to you, rather than letting inertia make the decision by default. Scripture doesn't call us to be anxious about money, but it does call us to plan with diligence rather than drift (Luke 14:28). A pre-tax IRA that's never been touched isn't a finished plan—it's an unfinished decision, and the gap years are often the best chance you'll get to finish it wisely.
This is exactly the kind of decision Kingdom Advisors trains financial professionals to walk through with clients—where a technical tax strategy and a biblical view of stewardship point in the same direction rather than pulling apart. As a Certified Kingdom Advisor (CKA®), that's the lens I try to bring to conversations like this one.
This strategy works best alongside the rest of your retirement picture—see our age-by-age retirement checklist for how RMDs and Social Security fit into the bigger timeline, and our guide to Qualified Charitable Distributions if giving is also part of your plan once RMDs begin. If you'd rather think through the biblical side of this season of life first, we've also written on what the Bible says about retirement.
Every retiree's gap years look a little different depending on pension income, when you plan to file for Social Security, and how large your pre-tax balances are. If you're in or approaching this window and haven't run the numbers, it's worth a conversation before the opportunity narrows.
Frequently Asked Questions About Roth Conversions in the Gap Years
What's the difference between a Roth conversion and a Roth contribution?
A contribution is new money you add to a Roth IRA directly, subject to annual limits and income caps. A conversion moves existing money from a traditional, pre-tax account into a Roth IRA, with no income limit and no annual dollar cap—you simply pay ordinary income tax on the amount converted in the year you convert it.
How much should I convert each year?
There's no single right number. The typical goal is to convert enough to use up the remaining room in your current tax bracket without pushing into the next one, repeated over several years of the gap rather than done all at once.
Can I still convert after RMDs begin?
Yes, but with a catch: once RMDs start, you must satisfy that year's full RMD before any additional withdrawal counts toward a conversion. That makes conversions less efficient after RMDs begin, which is exactly why the gap years beforehand are so valuable.
Will a Roth conversion affect my Social Security benefit?
It won't change the benefit amount you've earned, but it can affect how much of your Social Security is taxable in the year you convert, since it adds to your provisional income. This is one reason converting before you file for benefits often works out more cleanly.
Is it better to convert a large amount at once or spread it out?
Spreading conversions across several years of the gap, filling up a target tax bracket each year, almost always beats one large conversion, which risks pushing a big chunk of the converted amount into a much higher bracket in a single year.
What if I need the converted money before five years are up?
If you're over 59½, you can generally access converted funds without penalty at any time; the five-year rule mainly governs whether the earnings on those funds are withdrawn completely tax-free. It's worth reviewing your specific situation before assuming either way.
Does a Roth conversion make sense for everyone?
No. If you expect to be in a lower tax bracket throughout retirement than you are today, or if you don't have funds outside the IRA to pay the conversion tax, converting may not be the right move. It's a strategy worth running the numbers on, not a default decision.
Josh Salway is a financial advisor and founder of Full of Grace Financial, and a Certified Kingdom Advisor (CKA®), helping Christian families and business owners align their faith with their finances. This article is for informational purposes only and is not intended as tax or legal advice. Please consult your tax advisor or CPA regarding your specific situation.
