After-tax retirement, after both taxes are paid.
Pre-tax (Traditional / RRSP / Salary-Sacrifice) wins when retirement rates are lower than today. After-tax (Roth / ISA / TFSA) wins when retirement rates are higher. Plug your numbers — the math doesn't care what the account is called.
Built and reviewed by Stephen Omukoko Okoth
Mathematical Economist · ex-Morgan Stanley FI · Equilar
Inputs
Contribution
Roth equivalent today: $ 11,400 after paying 24% tax.
Tax rates
Marginal rate now vs in retirement
Growth
Years & return
Verdict
Traditional wins by $ 61.0K
Lower rate in retirement → Traditional's deferral wins. Capture the deduction now, pay less later.
Both calcs assume the same pre-tax contribution. The Roth case implicitly "costs more" out of pocket today by the tax slice — equal-effort comparisons would add the year-1 Traditional tax refund into your taxable account, which most households don't reinvest in practice.
Result
After 30 years
Traditional balance
$ 1.52M
Pre-withdrawal-tax
Traditional after tax
$ 1.22M
Roth balance
$ 1.16M
Tax-free at withdrawal
Difference
$ 61.0K
in favour of Traditional
Common questions
When does Roth (after-tax) beat Traditional (pre-tax)?
When your marginal tax rate in retirement will be higher than today. Younger, lower-income years are the classic Roth sweet spot — pay the (low) tax now, withdraw tax-free later. The same logic applies to UK ISAs, Canadian TFSAs, and South African TFSAs versus their tax-deferred counterparts.
When does Traditional beat Roth?
When your marginal rate today is higher than your retirement rate. High-earners in their peak years often prefer the immediate deduction; they expect to retire into a lower bracket. RRSPs (Canada), salary-sacrifice pensions (UK/AU/KE), and 401(k)s all qualify.
What if I don't know future tax rates?
You can't — so split. Many practitioners hold both buckets so they have tax-rate optionality in retirement: pull from Traditional in low-income years, Roth in high-income years. This is one of the most under-appreciated benefits of having both.
Does the calculator account for required minimum distributions (RMDs) or estate planning?
No — it focuses on the contribution-vs-withdrawal tax wedge. RMDs (in the US), inheritance tax, and trust structures can change the calculus, especially for very high net-worth households. Treat this as the core decision; layer those nuances after.