Roth IRA Conversions: Is Paying Taxes Now Worth the Future Growth?

Deciding whether to convert your Traditional IRA to a Roth IRA is one of the most significant tax moves an investor can make. The core of this decision relies on a simple gamble: you are betting that your tax rate today is lower than it will be in retirement. With current tax cuts set to expire soon, calculating the “breakeven point” involves more than just guessing future income; it requires looking at specific tax bracket thresholds and legislative timelines.

The Urgency: The Tax Cuts and Jobs Act Expiration

The primary driver for considering a Roth conversion right now is the looming expiration of the Tax Cuts and Jobs Act (TCJA). Unless Congress acts, current income tax rates are scheduled to sunset after December 31, 2025.

Currently, the tax brackets are historically favorable. For example, the 22% bracket covers a wide range of income, and the 24% bracket extends up to taxable incomes of $383,900 for married couples filing jointly in 2024.

If the TCJA expires, these rates revert to pre-2018 levels starting in 2026:

  • The 12% bracket likely jumps to 15%.
  • The 22% bracket likely increases to 25%.
  • The 24% bracket likely moves to 28%.

If you fall into the current 22% or 24% brackets, converting now effectively locks in a “discount” on your taxes compared to the probable rates three years from now.

Calculating the Mathematical Breakeven

Many investors misunderstand the math behind Roth conversions. They assume they need massive growth to justify the upfront tax bill. However, due to the commutative property of multiplication, if your tax rate is identical at contribution and withdrawal, the net result is the same.

Here is the math using a $50,000 IRA balance over 20 years with 7% growth, assuming a 24% tax rate at both times:

Scenario A: Keep in Traditional IRA (Tax Deferred)

  1. Principal: $50,000
  2. Growth (20 years @ 7%): Balance grows to roughly $193,484.
  3. Tax at Withdrawal (24%): You pay $46,436 in taxes.
  4. Net Value: $147,048.

Scenario B: Convert to Roth (Tax Now)

  1. Principal: $50,000
  2. Tax Paid Now (24%): You pay $12,000 (paid from outside funds to maximize efficiency).
  3. Growth (20 years @ 7%): The $50,000 grows to $193,484.
  4. Tax at Withdrawal: $0.
  5. Net Value: $193,484 (minus the opportunity cost of the $12,000 tax payment).

If you invested that $12,000 tax payment elsewhere at the same 7% rate, it would have grown to $46,436.

  • $193,484 (Roth) - $46,436 (Lost growth on tax money) = $147,048.

The Conclusion: The “breakeven” point is immediate if tax rates stay the same. You only win if your tax rate at withdrawal is higher than your tax rate today. If you pay 24% now to avoid paying 28% or 32% later (due to RMDs or tax law changes), the conversion is profitable.

"Bracket Topping": The Strategic Approach

You do not need to convert your entire IRA at once. In fact, doing so is often a mistake because it can push you into a tax bracket that makes the conversion too expensive.

The most effective strategy is “bracket topping.” This involves converting just enough funds to fill up your current tax bracket without spilling over into the next, higher one.

Example for 2024 Tax Year (Married Filing Jointly): The 22% tax bracket ends at a taxable income of $190,750. If your taxable income is $140,000, you have a “gap” of $50,750 before you hit the 24% bracket.

  • Strategy: You convert exactly $50,750 to a Roth IRA.
  • Result: You pay 22% on that money. If you converted $60,000, the last $9,250 would be taxed at 24%, reducing the efficiency of the move.

Hidden Costs: The IRMAA Cliff

When calculating your breakeven, you must look beyond federal income tax. Roth conversions increase your Modified Adjusted Gross Income (MAGI) for that specific year. This can trigger the Income-Related Monthly Adjustment Amount (IRMAA), which is a surcharge on Medicare Part B and Part D premiums.

Medicare looks at your tax return from two years prior. A large conversion in 2024 will affect your Medicare premiums in 2026.

The 2024 IRMAA Thresholds: For a married couple, the standard Medicare Part B premium is $174.70 per month. However, if your MAGI crosses $206,000, your premium jumps to $244.60 per month per person.

If a Roth conversion pushes your income from $200,000 to $210,000, you trigger this surcharge. For a couple, that creates an additional annual cost of nearly $1,700 in premiums. You must factor this “phantom tax” into your breakeven calculation.

When a Conversion Does NOT Make Sense

While the fear of rising taxes makes conversions popular, there are specific scenarios where paying the tax now is a mathematical loss:

  • You plan to move to a tax-friendly state: If you currently live in a high-tax state like California (up to 13.3% state tax) or New York but plan to retire in Florida or Texas (0% state income tax), paying taxes now is unwise. You are voluntarily paying a state premium you could avoid by waiting.
  • Charitable Giving (QCDs): If you plan to donate to charity in retirement, you can use Qualified Charitable Distributions (QCDs) from a Traditional IRA starting at age 70½. QCDs satisfy Required Minimum Distributions (RMDs) without counting as taxable income. If you convert that money to Roth now, you pay taxes on money that could have been donated tax-free later.
  • Short Time Horizon: If you need to access the funds within five years, you should be cautious. Each Roth conversion has its own five-year aging period before the principal can be withdrawn penalty-free (if you are under 59½).

Frequently Asked Questions

Can I undo a Roth conversion if the market crashes? No. The Tax Cuts and Jobs Act eliminated the ability to “recharacterize” (undo) a Roth conversion. Once you convert the funds and pay the tax, the decision is final.

Does the 5-year rule apply to conversions? Yes. There are two 5-year rules. The first dictates that the Roth account itself must be open for five years to withdraw earnings tax-free. The second applies specifically to conversions: each conversion has its own 5-year clock. If you withdraw converted principal before five years have passed (and you are under 59½), you may be hit with a 10% penalty, even though you already paid income tax on it.

How do I pay the tax bill on the conversion? Ideally, you should pay the tax bill using cash from a savings or brokerage account, not from the IRA funds themselves. If you use IRA funds to pay the tax, that portion is considered an early distribution (subject to taxes and potential penalties) and it reduces the amount of capital you have growing tax-free in the Roth.

Does a Roth conversion reduce my Required Minimum Distributions (RMDs)? Yes. Roth IRAs do not have RMDs during the account holder’s lifetime. By moving money from Traditional to Roth, you lower the balance of your tax-deferred accounts, thereby lowering the RMDs you will be forced to take at age 73.