The Tax Diversification Argument
Having both Roth and Traditional accounts gives you control over your taxable income in retirement. You can draw from Traditional when you need additional taxable income (filling lower brackets) and draw from Roth when more income would push you into a higher bracket. This flexibility is worth significant tax savings over a 20-30 year retirement.
Roth vs. Traditional allocation options and their characteristics
| Portfolio Mix | Flexibility | Best For | RMD Risk |
|---|---|---|---|
| 100% Traditional | None — all taxable | Near-retirement high earners | High — large RMDs |
| 75% Traditional / 25% Roth | Some flexibility | Those in 24%+ bracket currently | Moderate |
| 50% Traditional / 50% Roth | Good flexibility | Most savers — target allocation | Manageable |
| 25% Traditional / 75% Roth | High flexibility | Young savers in low brackets | Low |
| 100% Roth | Maximum flexibility | Lowest-income earners or estate-focused | None |
The 50/50 Target Allocation
For most working Americans a 50/50 Roth/Traditional allocation is a reasonable target. In practice this often means: max Roth IRA each year ($7,000) plus Traditional 401k contributions for the deduction value above what the IRA covers. This combination provides both current tax savings and future tax-free income.
You build Roth assets through annual Roth IRA contributions and Roth 401k options. You build Traditional assets through 401k contributions and Traditional IRA (when deductible). Over a 30-year career both buckets grow to meaningful size, giving you maximum retirement flexibility.
Tax diversification buildup: Roth + Traditional over a career
| Year | Annual Roth Contribution | Annual Traditional 401k | Total Saved | Balance Projection at 7% |
|---|---|---|---|---|
| 25 | $7,000 Roth IRA | $12,000 Traditional 401k | $19,000 | Starting |
| 35 | $7,000 Roth IRA | $15,000 Traditional 401k | $22,000 | $322,000 total |
| 45 | $7,000 Roth IRA | $23,500 Traditional 401k | $30,500 | $1,010,000 total |
| 55 | $8,000 Roth IRA | $31,000 Traditional 401k | $39,000 | $2,280,000 total |
When 100% Roth or 100% Traditional Is Right
100% Roth is correct when you are consistently in the 12% or lower bracket — taxes will almost certainly be higher throughout your life and in retirement. 100% Traditional is rarely the right answer in 2025 but could apply to peak earners in 37% brackets who genuinely expect to retire on modest income with an effective rate below 22%.
- 12% bracket and below: 100% Roth is usually optimal
- 22% bracket: 75%-100% Roth is usually best with some Traditional 401k for employer match capture
- 24% bracket: 50/50 split typically works well
- 32%+ bracket: 60%-75% Traditional plus backdoor Roth for diversification
- 37% bracket: primarily Traditional plus backdoor Roth IRA for flexibility
Find Your Optimal Roth vs. Traditional Split
Enter your income, bracket, and years to retirement to see your ideal Roth vs. Traditional allocation.