Short answerTraditional accounts give the tax break now. Roth accounts give it later. The trade favors whichever side faces the lower tax rate.
The core trade
Traditional contributions come from pre-tax income. You skip tax today and pay income tax on withdrawals.
Roth contributions come from after-tax income. You pay tax today and qualified withdrawals come out tax-free.
Both grow without yearly tax drag. The only question is when the IRS takes its cut.
The one question that decides
Compare your tax rate now to your rate in retirement. The trade favors paying tax in the lower-rate year.
A high-earning year makes the traditional deduction valuable. A low-earning year makes Roth's pay-now price cheap.
Nobody knows future rates for sure. Splitting contributions between both is a middle path for uncertain futures.
Where each account lives
Both flavors exist as IRAs and as 401(k)s. The 2026 IRA limit is $7,500, or $8,600 at 50 and older.
High earners face Roth IRA income limits: $153,000 to $168,000 single, $242,000 to $252,000 married filing jointly.
New for 2026: 401(k) catch-up contributions must be Roth when prior-year wages topped $150,000.
Withdrawals and timing
Traditional 401(k) and IRA withdrawals count as taxable income. Required withdrawals start at age 73.
Roth IRA withdrawals of contributions are always tax-free. Earnings come out tax-free after five years, once you reach 59 and a half.