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Devin has $7,500, one IRA contribution year, and a tempting shortcut: use a taxable brokerage account because his capital gains are tax-free today and the Roth looks pointless.
Zero percent is zero percent. But the cost of a missed Roth IRA contribution is not set by today’s rate alone; one tax return cannot tell Devin what the next thirty years will look like.
In this article’s base case, putting the same $7,500 in a taxable brokerage account instead of an eligible Roth IRA leaves Devin with $8,834 less in nominal after-tax value after thirty years. The model assumes a 7.00% annual return, 15% federal tax on qualified dividends each year, and 15% on the gain when the taxable position is fully sold. This is one tax path, not a universal cost. If every modeled dividend and the final gain avoid federal tax, the two accounts finish at the same value.
Devin’s expiring contribution year
Devin is 33. He has at least $7,500 of taxable compensation, has made no other 2026 IRA contribution, and qualifies for the full direct Roth contribution. The money is intended for retirement, but he is considering putting it in a brokerage account instead.
That choice looks reversible. It is not. Devin can move brokerage money later, but he cannot carry unused 2026 IRA room into 2027. The contribution deadline is the due date of his 2026 federal return, not including extensions. IRS Publication 590-A explains the deadline, and IRS Notice 2025-67 sets the 2026 IRA limit at $7,500.
| Input | Base case |
|---|---|
| Contribution | $7,500 at the start of 2026 |
| Holding period | 30 full years |
| Annual total return | 7.00% |
| Return split | 5.75% price growth + 1.25% qualified dividend |
| Dividend tax | 15% each year |
| Tax at sale | 15% on the long-term gain after a full sale in year 30 |
| State tax, net investment income tax, fees, inflation | Excluded |
For the first few years, the choice barely looks consequential.
At 40, the gap is $704, small enough to dismiss. At 50, it reaches $2,658. At 60, it is more than $6,800. By 63, the same fund and the same gross return leave Devin with $57,092 in the Roth and $48,257 after a hypothetical full sale in the taxable account.
| Age | Roth IRA | Brokerage after full sale | Gap |
|---|---|---|---|
| 40 | $12,043.36 | $11,339.80 | $703.56 |
| 50 | $23,691.11 | $21,033.40 | $2,657.72 |
| 60 | $46,604.01 | $39,770.64 | $6,833.36 |
| 63 | $57,091.91 | $48,257.49 | $8,834.42 |
Method in brief: I compound one $7,500 contribution for thirty annual periods. The Roth receives 7.00% each year. The taxable leg receives 5.75% price growth plus a 1.25% year-end qualified dividend, pays 15% on that dividend before reinvestment, adds the reinvested amount to basis, and sells the full position at a 15% long-term rate in year 30. State tax, the Net Investment Income Tax (NIIT), fees, inflation, and future law changes are excluded. This is scenario arithmetic, not a return forecast or individualized tax estimate.
The Roth did not find a better investment. It simply kept more money compounding.
How $1,284 of tax becomes a $2,926 cost
The first dividend-tax bill is $14.06. Even in year 30, it is only $95.08. Added together, Devin pays $1,284.37 of dividend tax across the full period.
But the year-30 cost of those annual tax payments is $2,926.30. The extra $1,641.93 is not another tax. It is the growth those dollars never had the chance to earn.
| Part of the gap | Year-30 amount |
|---|---|
| Annual dividend tax plus the growth it no longer earns | $2,926.30 |
| Capital-gains bill remaining at the full sale in year 30 | $5,908.12 |
| Total base-case gap | $8,834.42 |
That distinction matters. If dividends were untaxed and only the final sale faced a 15% rate, the sale-only gap would be $6,110.43, not $5,908.12. The base case pays dividend tax first, which leaves a slightly smaller final gain. The two rows above add to the total because the second row is defined as the capital-gains bill remaining after the dividend-tax path has already happened.
Why today’s 0% bracket is not the answer
This is the objection worth taking seriously. If qualified dividends and the final gain truly remain federally tax-free, the brokerage account matches the Roth in this model.
For a single filer in 2026, the zero-rate long-term capital-gains band ends at $49,450 of taxable income, and the 15% band runs through $545,500. Those are annual thresholds from IRS Revenue Procedure 2025-32, not a permanent label attached to an investor.
Take the 2026 standard deduction of $16,100. A wage-only single filer earning $65,550 reaches $49,450 of taxable income before qualified dividends are added. Absent other adjustments, none of those dividends would remain in the zero-rate band. Business income, deductible IRA contributions, Health Savings Account (HSA) contributions, interest, and capital losses can all change the result, so the actual return matters more than a salary shortcut.
Line 15 of Form 1040 tells Devin what happened in one filing year. It does not set the dividend rate for the next three decades, and it says nothing about the rate in the year he finally sells.
The 2026 direct Roth IRA phaseout for a single filer runs from $153,000 to $168,000 of modified AGI. Workplace-plan coverage can affect a traditional IRA deduction, but it does not by itself disqualify a direct Roth contribution. Above the direct phaseout, review the backdoor Roth IRA rules and the pro-rata rule before contributing.
How different tax paths change the result
The base case is one path. The useful test is how far the result moves when the tax path changes while the investment return stays the same.
| Tax path | Brokerage after full sale | Gap |
|---|---|---|
| 15% on dividends and final gain | $48,257.49 | $8,834.42 |
| Zero federal tax on dividends and final gain | $57,091.91 | $0.00 |
| 15% on dividends, zero federal tax at sale | $54,165.61 | $2,926.30 |
| Zero federal tax on dividends, 15% at sale | $50,981.48 | $6,110.43 |
| 20% statutory rates, NIIT excluded | $45,433.00 | $11,658.92 |
The clean tie is the all-zero row. Miss either half of that path and the gap reopens. Paying dividend tax but selling in a zero-rate year still costs $2,926. Paying no dividend tax but selling at 15% still costs $6,110.
Time matters more. Under the base assumptions, the gap grows from about $3,600 after twenty years to nearly $19,900 after forty. Holding total return constant while raising the dividend yield from 0.75% to 2.00% widens the thirty-year gap by about $1,365.
When a brokerage account can still be the right account
A brokerage account is not the villain here. The model prices the value of tax sheltering one contribution year; it does not decide Devin’s entire financial plan.
Brokerage money has no annual contribution cap, no retirement-account withdrawal restrictions, and no required minimum distributions. It also allows tax-loss harvesting. Those advantages can matter more than the modeled tax drag when the money has a nearer job.
Roth money is also less rigid than “locked until 59½” suggests. Under the federal ordering rules, regular contributions across a person’s Roth IRAs are treated as coming out before conversions and earnings. That makes the contribution layer relatively accessible; the earnings layer is where age, five-year, and exception rules matter. IRS Publication 590-B gives the full ordering rules.
| Situation | Likely priority |
|---|---|
| Retirement money that can stay invested | Use eligible Roth room before the tax year closes. |
| Money whose gains may be needed for an earlier goal | Use the brokerage account for full flexibility. |
| Savings above the annual IRA limit | Fill available Roth room, then route the excess elsewhere. |
| Need for tax-loss harvesting | Use a brokerage account; a Roth cannot produce realizable tax losses. |
The deadline is real, but it is not permission to drain the emergency fund. If filling the Roth would force Devin to pull the money back out for next month’s bills, the account is not solving the right problem. The broader tradeoffs are covered in the brokerage account vs IRA guide.
Common questions
Does unused Roth IRA contribution room carry forward?
No. IRA limits apply by tax year. An eligible 2026 contribution can generally be made through the filing deadline for the 2026 return, not including extensions, but unused room is not added to the 2027 limit. Devin can invest the cash elsewhere later; he cannot recreate the skipped 2026 IRA slot.
What if I never sell the brokerage position?
Then the $5,908.12 sale-year tax remains unpaid and the two account balances sit about $2,926 apart. That is not an after-tax tie: it compares an unsold taxable balance carrying an embedded tax with a Roth balance that can be spendable tax-free under the model. The tax is deferred, not canceled. Partial sales, losses, gifts, and a basis adjustment at death can change the path.
Does the 0% capital-gains bracket make the accounts identical?
Only when the modeled tax path actually stays at 0% for every qualified dividend and for the final gain. A 0% rate this year can reduce or eliminate this year’s tax, but it does not guarantee the rate during later working years or at the eventual sale.
The bottom line
Devin’s choice does not carry a universal $8,834 price tag. Over the same thirty years, the modeled gap ranges from $0 under a fully tax-free path to about $11,700 under the 20% statutory-rate sensitivity. Stretch the base case to forty years and it widens to nearly $19,915.
What Devin cannot recover is the contribution year. If the money is truly for retirement, he is eligible, and he does not need the earnings for an earlier goal, the expiring Roth space has value even when today’s capital-gains rate is zero.
If he may need the full balance sooner, the brokerage account can still be the right choice. The better account depends on what the money must do, not on one line from this year’s tax return.
Before choosing: Name the money’s job: retirement, or a goal that may require the gains sooner. That answer should come before the tax-bracket shortcut.
- Thirty years of recurring contributions; this is one contribution year.
- Monthly funding, irregular returns, sequence effects, and behavioral changes.
- Partial sales, tax-loss harvesting, charitable gifts, and a potential basis adjustment at death.
- Capital-gain distributions, nonqualified dividends, portfolio turnover, and investor trading.
- State tax, NIIT, fees, inflation, and future law changes.
- IRS Revenue Procedure 2025-32: 2026 long-term capital-gains thresholds and standard deduction.
- IRS Notice 2025-67: 2026 IRA contribution limit and Roth IRA income phaseout.
- IRS Publication 590-A: IRA contribution eligibility and deadline rules.
- IRS Publication 590-B: Roth IRA distribution ordering rules.
AI assisted with drafting and consistency checks. Danny Hwang verified the IRS sources, rebuilt every calculation, and is responsible for the final analysis.
Update history
- August 4, 2026: Published after calculation review, source verification, and an editorial pass that clarified the residual gap decomposition and the unsold-balance comparison.
Educational quantitative analysis based on published data. Not investment, tax, or legal advice. Consult a licensed professional before acting on any calculation. About TheFinSense.