Roth Conversion vs. Roth Contribution: Which Strategy Wins If Tax Rates Rise?

The debate between Roth conversions and Roth contributions is not about philosophy, but about math. Both strategies put money into a Roth IRA or Roth 401(k) where it grows tax-free and comes out tax-free. They use different dollars and face different limits. When tax rates rise, the outcomes diverge sharply. Most people confuse the two. Some think a conversion is just a big contribution. Others think you have to pick one or the other. Neither is true.

TL;DR: Roth conversions move existing pre-tax money into a Roth account, and there is no annual cap on how much you can convert. Roth contributions add new after-tax money, up to the annual IRS limits and, for a Roth IRA, within the income phase-out. If the rate you pay today is lower than the rate you expect to pay later, either route can help. Which one fits depends on your current versus expected future marginal rate, whether you are eligible to contribute or deduct, whether you have cash outside the account to pay conversion tax, your liquidity, and your own circumstances. The PenaltyFreeRetire Roth Conversion Ladder calculator provides a simplified federal planning illustration based on the assumptions you enter. It does not model every tax-return item, state tax, ACA premium tax credits, Medicare IRMAA, or future changes in the law.

What is a Roth conversion and how does it differ from a Roth contribution?

A Roth conversion moves money you already hold in a pre-tax account, such as a Traditional IRA, a Traditional 401(k), or a rollover IRA, into a Roth IRA. You pay ordinary income tax on the converted amount in the year you move it. After that, the money grows tax-free and qualified withdrawals in retirement are tax-free.

A Roth contribution is different. You take money from your paycheck or bank account, money you have already paid tax on, and deposit it into a Roth IRA or Roth 401(k). You get no tax deduction now. The trade-off is tax-free growth and tax-free qualified withdrawals later.

The key difference is the source of the money. A conversion re-characterizes existing pre-tax dollars. A contribution adds new after-tax dollars. Both end up in a Roth account, but the path, the tax timing, and the rules are not the same.

The mechanics: pre-tax vs after-tax dollars, income limits, annual limits

Roth contributions have strict annual caps. In 2026, you can contribute $7,500 to an IRA, or $8,600 if you are 50 or older, because the IRA catch-up of $1,100 is now indexed for inflation under SECURE 2.0. A Roth 401(k) sits inside a larger limit. The elective deferral limit for 401(k), 403(b), and governmental 457(b) plans is $24,500 in 2026, or $32,500 once you add the general age 50 catch-up of $8,000.

SECURE 2.0 added a third tier that is easy to miss: the higher catch-up for ages 60 through 63. Where the plan allows it and you are eligible, the catch-up in that four-year window is $11,250 in 2026 rather than the general $8,000, which brings the total elective deferral limit to $35,750. The higher catch-up stops applying the year you turn 64, and the general $8,000 catch-up applies again from that point.

The higher catch-up matters for this comparison because it changes how fast new money can enter Roth space for people in that age band. Someone aged 60 to 63 whose plan offers it can defer more in a single year than a 50-year-old colleague can. It does not change the underlying question, which is whether the rate you pay on a dollar today is lower than the rate you expect to pay on that same dollar later.

One related SECURE 2.0 wrinkle hits the same group. Starting in 2026, if your prior-year FICA wages from that employer exceeded $145,000 (indexed, roughly $150,000 for the 2025 lookback), your 401(k) or 403(b) catch-up contributions, including the higher age 60 to 63 catch-up, must be made as Roth contributions, not pre-tax. For those workers the pre-tax versus Roth choice is already settled by statute at the catch-up level, so the conversion-versus-contribution question does not arise on those particular dollars. It still arises on everything else, and the answer there turns on the rate comparison and on where the tax money comes from.

These limits reset every year. You cannot carry unused room forward.

Roth contributions also have income limits for Roth IRAs. In 2026, the phase-out for single filers starts at $153,000 and ends at $168,000. For married couples filing jointly, it starts at $242,000 and ends at $252,000. Above those ceilings, you cannot contribute directly to a Roth IRA. A Roth 401(k) has no income limit.

Roth conversions have no annual limit. You can convert $10,000 or $1,000,000 in a single year. The IRS does not cap conversions because you are paying tax now, not deferring it. You can convert at any income level. There is no earned income requirement. You can be retired or unemployed and still convert.

Conversions also have no age limit. You can convert at 35 or 75. The only restriction is that you must wait five years before withdrawing converted principal penalty-free if you are under 59½. The Roth Conversion Ladder strategy relies on this five-year sequencing rule.

The core argument: why rising tax rates change the math

The basic Roth promise is simple. Pay tax now at your current rate so you do not pay tax later at whatever rate applies in retirement.

If your tax rate stays the same, a Roth account and a Traditional account produce the same ending value for the same pre-tax dollar. The math is indifferent.

If your tax rate drops in retirement, the Traditional account wins. You deferred tax at a high rate and paid it at a low rate.

If your tax rate rises in retirement, the Roth wins. You locked in a lower rate today and avoided a higher rate tomorrow.

Tax rates rise for a few common reasons. Congress can always raise rates, so future policy risk is real. More predictably, inflation-adjusted bracket thresholds climb more slowly than some incomes, which means bracket creep pushes people into higher marginal rates over time. Retirees are especially vulnerable: required minimum distributions, Social Security, and pensions stack on top of each other and can fill the lower brackets, leaving Traditional IRA withdrawals to be taxed at higher marginal rates.

When the rate you expect later is higher than the rate you pay now, both Roth contributions and Roth conversions look attractive. How much each one helps depends on your rates, your eligibility, and how much money each route can actually move.

A concrete numerical example comparing both strategies side-by-side

Here is a simplified illustration rather than a prediction. Alex is 50, single, earns $85,000 a year, and holds $300,000 in a Traditional 401(k) from past jobs. His current marginal federal rate is 22%. He assumes his marginal rate on retirement withdrawals will be 28% once bracket creep, Social Security, and required minimum distributions stack up. Both strategies below use the same assumptions: a 15-year horizon, 7% annual growth, a 15% long-term capital gains rate on the taxable account, conversion tax paid from cash held outside the retirement accounts, and a conversion small enough to stay inside his current bracket.

He has $25,000 of after-tax cash to put toward retirement this year, and each strategy below spends all $25,000.

Strategy A: Roth contribution only

He contributes $8,600 to his Roth IRA, the 2026 maximum at age 50, and puts the other $16,400 into a taxable brokerage account. After 15 years at 7%, the Roth IRA holds about $23,700, all of it tax-free. The taxable account grows to about $45,200, and after 15% tax on the $28,800 gain it is worth roughly $40,900. That is about $64,600 from this year's $25,000. The $300,000 Traditional 401(k) is untouched, so it grows to about $827,700 and is worth about $595,900 after 28% tax on withdrawal. Strategy A total: roughly $660,500.

Strategy B: Roth conversion

He converts $25,000 from the Traditional 401(k) to a Roth IRA and pays the 22% tax of $5,500 out of the same $25,000 of cash. The remaining $19,500 goes into the taxable brokerage account. After 15 years at 7%, the converted money is worth about $69,000 and comes out tax-free. The taxable account grows to about $53,800, and after 15% tax on the $34,300 gain it is worth roughly $48,700. The Traditional 401(k) is now $275,000, which grows to about $758,700 and is worth about $546,300 after 28% tax. Strategy B total: roughly $664,000.

Both paths spend the same $25,000 of after-tax cash over the same 15 years at the same growth rate, and both pay tax out of the same pocket. Strategy B finishes about $3,500 ahead, well under 1% of the combined total. The gain comes from paying 22% instead of 28% on $25,000 of pre-tax money, partly offset by giving up the Roth contribution and its tax-free wrapper on $8,600.

The whole edge rests on the 6 percentage point gap between the 22% he pays now and the 28% he assumes later. Narrow that gap and the advantage shrinks toward nothing. Reverse it, so that his retirement rate lands below 22%, and Strategy A comes out ahead instead. The size of the 401(k) is not what drives the result. The rate spread is.

Account size changes only how long each route takes. Contributions are capped every year, so new money enters Roth space at a fixed pace. Conversions are not capped, so the same dollars can move over a handful of years instead of decades. That is a point about speed, not a reason on its own to convert.

The PenaltyFreeRetire Roth Conversion Ladder calculator can help you test this comparison with your own inputs. Enter your balance, your rate today, and the rate you expect in retirement. It produces a simplified federal planning illustration based on those assumptions. It does not model every item on a tax return, state tax, ACA premium tax credits, Medicare IRMAA, or future changes in the law, so treat the output as directional rather than an exact result or a guarantee.

When Roth contributions make more sense

Roth contributions are often the better fit in a few specific situations.

If you are young and in a low tax bracket, contributions are hard to beat. For a 25-year-old in the 12% bracket, today's rate is probably as low as it will ever be, and there are decades of growth ahead for the money to compound tax-free.

If you hold little or no pre-tax money, contributions are your only route into a Roth account. You cannot convert what you do not have.

If you expect your income to rise significantly, front-load Roth contributions while your rate is low. Medical residents, graduate students, and early-career workers fit this pattern.

If you cannot pay the tax bill on a conversion from cash outside the retirement account, contributions are usually the more practical route. Conversions require outside cash to pay the tax, and if paying it would drain your emergency fund or force you into debt, converting is generally not a good fit.

When Roth conversions make more sense

Conversions tend to look better when you hold pre-tax money and expect the rate on those dollars to be higher later than the rate you would pay on them now.

If the rate you would pay on a conversion this year is lower than the rate you expect to pay on the same dollars in retirement, a conversion is worth modelling. Contribution limits cap how fast new money can enter Roth space, while conversions are not capped, so conversions are often the only way to move pre-tax balances within a few years. Whether that is worth doing depends on the rate comparison, on having cash outside the account for the tax bill, and on the rest of your situation.

A temporarily low-income year is worth a second look. A job loss, a sabbatical, or an early retirement before RMDs begin can leave your income far below normal, and deductions such as the standard deduction can leave you with little or no taxable income for that year. A conversion then adds taxable income and fills the progressive brackets from the bottom up, so the first converted dollars are taxed at the lowest rates that apply to you before higher rates take over.

If you are over 59½, conversions become simpler. You can withdraw from the Traditional account to pay the conversion tax without penalty. You also do not have to worry about the five-year waiting period for converted principal.

The Rule of 55 exempts a distribution from a qualified employer plan from the 10% early-withdrawal penalty when your separation from service occurs during or after the calendar year you turn 55, and only if that plan's own terms allow such withdrawals. Each employer plan is evaluated separately, so a balance left behind at an earlier employer does not qualify. Qualified public safety employees and private-sector firefighters may use the earlier threshold of age 50 or 25 years of service where it applies. That access to cash for living expenses can free up other money to pay conversion taxes. Be careful not to roll that specific 401(k) into an IRA if you need that bridge, because doing so ends Rule of 55 access.

For the mechanics of how conversions actually work year-by-year, see our post on why the first five years make or break your Roth ladder.

Step-by-step how to think through the decision for your own situation

You do not need a spreadsheet. You need four numbers.

1. Find your current marginal tax rate. Look at last year's tax return. What was the highest bracket you touched?
2. Estimate your retirement tax rate. This is a guess, but make it an educated one. Consider bracket creep from inflation-adjusted thresholds, whether you will have pensions or rental income, and when Social Security and RMDs start. A reasonable default is your current rate plus two or three percentage points if you expect your taxable income in retirement to land in a higher bracket.
3. Check your pre-tax balance. Log into your Traditional IRA and 401(k) accounts and see how much sits in pre-tax dollars. That tells you how much is available to convert. It does not tell you whether converting is right for you, because the rate comparison decides that.
4. Check your cash position. Can you pay the conversion tax without touching the retirement money itself? You need cash outside the account. If you do not have it, you cannot convert.

If your expected retirement rate is higher than your current rate and you have pre-tax money to move, converting within your bracket headroom is worth modelling. The Roth Conversion Ladder calculator can illustrate how different conversion amounts interact with your bracket under the assumptions you enter, rather than identify a single correct number. How much to convert, if any, still depends on your marginal rate now and later, your eligibility, where the tax money comes from, your liquidity, and the rest of your situation. Roth contributions may fit alongside a conversion if you remain eligible.

If your expected retirement rate is lower than your current rate, the deduction from Traditional contributions may be worth more than moving money into Roth space now, though that depends on your eligibility to deduct, your other income, and what you expect later.

If your rates are the same, it does not matter much. Do whatever is simpler. Most people find Roth contributions simpler than conversions.

Common mistakes people make

• Converting without checking your bracket headroom. A $100,000 conversion sounds clean until part of it spills out of the 22% bracket into the 24% bracket and, if it is large enough, higher still. Every dollar above the line costs more than the dollars below it. Convert enough to fill your bracket, not enough to burst it.
• Paying conversion tax from the converted money. If you convert $50,000 and withhold $11,000 for taxes, only $39,000 makes it into the Roth. You just reduced your tax-free growth by 22%. Pay the tax from a separate savings or checking account.
• Ignoring the five-year rule. Each conversion has its own five-year clock. Convert in 2026 and the principal is penalty-free in 2031. Convert again in 2027 and that chunk is penalty-free in 2032. Track the dates or use the calculator timeline feature.
• Forgetting about Medicare IRMAA. Large conversions increase your modified adjusted gross income, which can trigger higher Medicare premiums two years later. If you are within two years of Medicare enrollment, model the IRMAA cost before converting.
• Converting everything at once. A $300,000 conversion in a single year can push much of the amount into higher brackets than a series of smaller conversions would. Whether to spread the conversions, and across how many years, depends on your bracket headroom, other income, health coverage, and how long your low-income window lasts. The ladder works when you run it deliberately each year, not because speed helps.

Use the PenaltyFreeRetire Roth Conversion Ladder calculator to build a simplified federal planning illustration for your own assumptions. Open Calculator

Frequently Asked Questions

Can I do both Roth conversions and Roth contributions in the same year?

Yes. There is no rule against it. If you are eligible to contribute, you can put $7,500 into a Roth IRA, or $8,600 if you are 50 or older, and convert $50,000 from a Traditional IRA in the same tax year. The contribution uses after-tax dollars. The conversion triggers tax on the pre-tax dollars you move.

Is there a limit on how much I can convert?

No. The IRS places no dollar cap on Roth conversions. You can convert $1,000 or $1,000,000. Your only practical limit is your tax bracket headroom. Convert too much and you pay a higher marginal rate on the spillover.

Do Roth contributions reduce my taxable income?

No. Roth contributions are made with after-tax dollars. They do not lower your taxable income in the year you make them. Traditional contributions do. A Roth 401(k) contribution also does not reduce your taxable income.

What is the five-year rule for Roth conversions?

Each conversion starts its own five-year clock. Convert in 2026, and you can withdraw that converted principal penalty-free starting January 1, 2031. If you are over 59½, the five-year rule on conversions no longer drives the penalty, although a separate five-year rule applies to Roth earnings regardless of age.

Can I convert if I'm still working?

You can convert a Traditional IRA at any time regardless of employment status. Converting an active 401(k) is harder, because most employer plans block in-service distributions or rollovers while you are still working and under 59½. Some plans allow in-plan Roth conversions. Check with your administrator. Once you separate from your employer, the 401(k) is free to roll over and convert.

What if tax rates don't rise?

Then the Roth advantage shrinks or disappears. If your retirement rate is lower than your current rate, you paid more than you needed to by converting or contributing to Roth. If rates stay flat, Roth and Traditional produce roughly the same result for the same pre-tax dollar. The Roth still offers flexibility, with no lifetime RMDs and tax-free inheritance for heirs, but the pure math is a wash.

Should I convert all at once or over several years?

It depends. Converting everything in one year often pushes more of the amount into higher brackets, and spreading conversions across several years can keep more of the total in lower brackets. The right pace depends on your bracket headroom, other income, health coverage, and how long the low-income window lasts. The calculator can illustrate different annual amounts under the assumptions you enter rather than identify one best answer.

How do I know what my tax rate will be in retirement?

You do not. No one does. Make a reasonable estimate. Look at your expected income sources, including Social Security, pensions, rental income, and RMDs, and map them against current brackets. Add a buffer for bracket creep and policy changes. Then test a few different rates in the calculator to see how sensitive the illustration is to your assumptions.

Sources

• IRS 2026 retirement limit announcement
• IRS 401(k) contribution limits
• IRS Notice 2025-67: 2026 Amounts Relating to Retirement Plans and IRAs
• IRS, Retirement topics: Exceptions to tax on early distributions
• IRS Publication 590-B, Distributions from Individual Retirement Arrangements (IRAs)
• IRS, Treasury and IRS issue final regulations on the new Roth catch-up rule

Disclaimer: The information on PenaltyFreeRetire is for general educational and informational purposes only. Nothing on this site constitutes financial, tax, legal, or investment advice. Tax laws change and individual circumstances vary. Consult a qualified CPA or fee-only financial planner before implementing any early withdrawal strategy. IRS Publication 575, Publication 590-B, Internal Revenue Code Section 408A and IRS Notice 2022-6 contain the authoritative rules.

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