VividTimelineTaxed once. The only difference is when.RothTAX$nowTraditionalTAX$later

Traditional vs Roth: How the Two Account Types Are Taxed

The VividTimeline Team4 min read
TaxesRoth vs TraditionalRetirement accountsHow money works

Traditional and Roth are the two tax treatments most retirement accounts fall under. They are not different investments. They are different rules for when the money is taxed, and once you see the timing, the rest follows.

The short version: the money is taxed once either way. Traditional taxes it on the way out. Roth taxes it on the way in.

The core difference is timing

A Traditional contribution goes in with pre-tax dollars. You skip income tax on that money in the year you contribute, the balance grows untaxed, and you pay ordinary income tax on every dollar you take out later.

A Roth contribution goes in with after-tax dollars. You pay income tax on the money in the year you earn it, the balance grows untaxed, and qualified withdrawals later are tax-free.

So the tax happens exactly once in both cases. The only thing that moves is when.

The difference is when tax is paidContributeGrowWithdrawTrad.Rothgoes ingrowsTAXTAXgrowstax-free
Traditional taxes the withdrawal. Roth taxes the contribution. Same tax, different moment.

The arithmetic when rates stay flat

Suppose you have 1,000 dollars of pre-tax income to direct into an account, your money grows 5 times over your holding period, and your income tax rate on that money (federal, plus any state income tax) is 22 percent both now and at withdrawal.

Same rate and growth, same resultTraditionalRothput in$1,000grows to$5,000tax-$1,100you keep$3,900tax first$780grows to$3,900withdrawtax-freeyou keep$3,900
With the same rate at both ends, both paths land on 3,900 dollars.
  • Traditional: the full 1,000 dollars goes in. It grows to 5,000 dollars. At withdrawal you pay 22 percent, leaving 3,900 dollars.
  • Roth: you pay 22 percent first, so 780 dollars goes in. It grows 5 times to 3,900 dollars, and withdrawals are tax-free, leaving 3,900 dollars.

Both land in exactly the same place. When the tax rate is identical at contribution and withdrawal, Traditional and Roth are mathematically equivalent. That is because multiplying by the growth factor and by the tax factor gives the same answer in either order.

What changes the outcome

Since the rate is the only thing that can break the tie, the comparison comes down to how your tax rate at withdrawal compares to your rate today:

  • If your rate at withdrawal is lower than today, the Traditional path keeps more, because the tax lands on withdrawals at that lower rate.
  • If your rate at withdrawal is higher than today, the Roth path keeps more, because the tax was locked in at the lower rate.
  • If the two rates match, the paths are equal, as shown above.

Try your own tax rates

$1,000 pre-tax, grown 5× to $5,000. Each percentage is your income tax rate on that money (federal, plus any state income tax).

Roth$3,900
Traditional$3,900

At these rates, both keep the same amount.

Drag the two rates. When they match, the paths tie; move one and that path pulls ahead.

Nobody knows their future tax rate with certainty, which is why this stays a genuinely open question rather than a solved one.

Other factual differences

A few mechanical distinctions beyond the core timing:

  1. Traditional accounts are subject to required minimum distributions starting at age 73 under current law. Roth IRAs are not subject to required minimum distributions during the original owner's lifetime.
  2. Roth contributions (not earnings) can generally be withdrawn without tax or penalty, because that money was already taxed.
  3. Some plans allow both, letting a saver split contributions across the two treatments.

Seeing it on your own timeline

These are the rules and the arithmetic, stated neutrally. Which treatment produces more after-tax money in your case depends on your own tax rates over time, something only your numbers can answer. VividTimeline models both treatments across every year of your plan so you can watch the after-tax balances diverge or converge based on the rates you enter.