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Tax Deferred Accumulation Calculator

Taxable against tax-deferred

Equal nominal contributions into both accounts. The taxable one is charged a modeled rate on its earnings every year; the deferred one is charged once, at the end.

Cash flows
End: the period's growth is credited, then the deposit lands. Start: the deposit lands first and earns that period's growth too. Both accounts use the same convention.
Optional. Year one uses the amount above; each subsequent year steps up by this much, in both accounts alike.
Return and modeled tax
Treated as an effective annual return: the period rate is its exact n-th root, so the contribution frequency never changes the annual return you assumed.
One modeled rate standing in for interest, dividends and realised gains together. It is charged at each year end on that year's investment earnings only — never on contributions or principal — and a losing year is charged nothing.
Applied once, to the tax-deferred account, at the comparison date.
Whole balance: the simplified pre-tax assumption, where every dollar is taxable on the way out. Earnings only: what a nondeductible contribution would leave behind. These are different economic models — see the note under the result.
Sensitivity band
Taxable path is higher after tax
$3,941

$347,444 after tax in the deferred account against $351,386 in the taxable one, on equal nominal contributions over 25 years at 6.00% a year. Under these assumptions only.

Taxable ending balance$351,386$55,701 of tax modeled along the way
Tax-deferred, before withdrawal tax$445,441Also the no-tax benchmark for the same cash flows
Tax modeled at withdrawal$97,99722.00% of the whole balance
Tax-deferred after tax$347,444
Cost of taxing along the way$94,05621.1% of the untaxed balance — $38,355 of it growth those taxes never earned
After-tax difference−$3,941-1.12% against the taxable balance

What equal contributions mean here. Both accounts receive the same nominal dollars. Because the withdrawal tax is applied to the whole deferred balance, the deferred contributions are being treated as pre-tax dollars — but no current-year deduction is credited for them. That understates a real deductible contribution, and it is why this setting can leave the taxable path ahead. Switch the base to earnings only to model contributions that were already taxed.

Modeled break-even withdrawal tax rate: 21.12%. Re-running the whole comparison at the exact solved rate leaves $0.00 between the two paths; typing the rounded 21.12% back into the field above leaves -$21.48, which is the two-decimal rounding on a $445,441 base. Your 22.00% sits above it, which is why the deferred path is behind here. It is a break-even point, not a recommendation.

Taxable account: what the modeled tax leaves behind
  • Contributions and starting balance: $175,000 (39.3%)
  • Growth kept: $176,386 (39.6%)
  • Tax modeled during accumulation: $55,701 (12.5%)
  • Growth those taxes would have earned: $38,355 (8.6%)
Tax-deferred account: the same money, taxed once at the end
  • Contributions and starting balance: $175,000 (39.3%)
  • Growth kept: $172,444 (38.7%)
  • Tax modeled at withdrawal: $97,997 (22.0%)
  • Growth those taxes would have earned: $0 (0.0%)
Where each path pays, and when
MeasureTaxable accountTax-deferred account
Contributions and starting balance$175,000$175,000
Gross investment growth modeled$232,086$270,441
Tax modeled during accumulation$55,701$0
Balance at the comparison date$351,386$445,441
Tax modeled at withdrawal$0$97,997
After-tax value$351,386$347,444

Nothing is modeled as paid by the deferred account during accumulation, and nothing by the taxable account at withdrawal. That timing is the whole comparison.

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After-tax difference under different assumptions (drag ±8 points, withdrawal rate ±8 points)
Annual drag ↓ / Withdrawal →14% at withdrawal22% at withdrawal30% at withdrawal
16% drag$3,082-$32,553-$68,188
24% drag (selected)$31,694-$3,941-$39,577
32% drag$57,881$22,246-$13,389

A positive figure means the tax-deferred path ends higher after tax. Heavier annual drag pushes the comparison toward deferral; a heavier withdrawal rate pushes it away.

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How time changes the cost of annual tax drag, at 24.00% a year
YearsTaxable ending balanceDeferred after-tax balanceDifferenceTax paid during accumulation
5$64,787$53,195-$11,592$3,091
10$114,512$98,286-$16,226$9,320
20$254,322$239,380-$14,942$34,523
30$472,692$492,058$19,366$84,534
40$813,766$944,566$130,799$173,295

Each row is a full run at that horizon, not an interpolation. The sign of the difference does not have to move in one direction: a terminal tax charged on principal costs the same fraction whenever it lands, while the compounding advantage keeps building.

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The same comparison across annual drag rates
Annual tax dragTaxable ending balanceTax paid along the wayDifference vs deferred
0.0%$445,441$0-$97,997
10.0%$403,186$25,354-$55,741
20.0%$365,374$47,594-$17,930
30.0%$331,530$67,084$15,915
40.0%$301,224$84,149$46,220

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Year by year
YearTaxable openingGross earningsTax paidContributionsTaxable endingDeferred endingTax to dateBalance gap
1$25,000$1,663$399$6,000$32,264$32,663$399$399
2$32,264$2,099$504$6,000$39,859$40,786$903$927
3$39,859$2,555$613$6,000$47,801$49,397$1,516$1,596
4$47,801$3,031$728$6,000$56,105$58,524$2,244$2,419
5$56,105$3,530$847$6,000$64,787$68,199$3,091$3,411
6$64,787$4,051$972$6,000$73,866$78,454$4,063$4,588
7$73,866$4,595$1,103$6,000$83,358$89,324$5,166$5,966
8$83,358$5,165$1,240$6,000$93,283$100,847$6,405$7,564
9$93,283$5,760$1,382$6,000$103,661$113,061$7,788$9,400
10$103,661$6,383$1,532$6,000$114,512$126,008$9,320$11,496
11$114,512$7,034$1,688$6,000$125,858$139,732$11,008$13,874
12$125,858$7,715$1,852$6,000$137,721$154,279$12,859$16,558
13$137,721$8,427$2,022$6,000$150,125$169,699$14,882$19,573
14$150,125$9,171$2,201$6,000$163,095$186,044$17,083$22,949
15$163,095$9,949$2,388$6,000$176,656$203,370$19,470$26,714
16$176,656$10,763$2,583$6,000$190,836$221,735$22,053$30,899
17$190,836$11,613$2,787$6,000$205,662$241,203$24,841$35,541
18$205,662$12,503$3,001$6,000$221,164$261,838$27,841$40,674
19$221,164$13,433$3,224$6,000$237,374$283,712$31,065$46,338
20$237,374$14,406$3,457$6,000$254,322$306,898$34,523$52,576
21$254,322$15,423$3,701$6,000$272,043$331,475$38,224$59,432
22$272,043$16,486$3,957$6,000$290,572$357,527$42,181$66,954
23$290,572$17,598$4,223$6,000$309,947$385,141$46,404$75,195
24$309,947$18,760$4,502$6,000$330,204$414,413$50,907$84,209
25$330,204$19,976$4,794$6,000$351,386$445,441$55,701$94,056

Every headline figure above is a total of these rows. Each year's tax is that year's gross earnings multiplied by the drag rate, charged at year end; the balance gap is measured before the withdrawal tax is applied.

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