Why After-Tax Returns Matter More Than Gross Returns

TL;DR

• Two investments with the same gross return can produce dramatically different after-tax wealth over 20–30 years depending on account type, tax treatment, and annual drag.
• A 7% gross return in a taxable account is not comparable to a 7% gross return in a Roth IRA. The Roth compound produces roughly 40% more after-tax wealth over 30 years at a 25% tax rate.
• The correct question for any investment is never “what is the return?” It is “what is the after-tax return, in which account, compared to the index alternative?”

The problem with gross return

Every fund fact sheet, brokerage statement, and financial headline quotes gross returns. Returns before fees, before taxes, before any consideration of the friction that actually determines what you keep.

This is not an accident. Gross return is simpler to calculate and more impressive to display. A fund that returned 9% gross and 6.2% after-tax, after fees, shows the 9%.

The gap between 9% and 6.2% feels small. Compounded over 30 years on $500,000, it is the difference between $6.6 million and $3.0 million. That is not a rounding error.

What tax drag actually is

Tax drag is the reduction in compound return caused by taxes paid along the way. It operates through three channels:

1. Annual income distributions Mutual funds and ETFs distribute dividends and capital gains. You pay tax on these distributions in the year received — whether or not you reinvested them. That tax payment leaves the account and reduces the compounding base.

An index ETF with a 1.5% dividend yield, taxed at 15% (qualified dividend rate), generates 0.225% of annual drag. That seems trivial. Over 30 years on a $1M portfolio, it is approximately $210,000 in foregone compounding.

2. Realized capital gains on sales Every time you sell a position at a gain, you owe tax. In a taxable account, rebalancing, tax-loss harvesting substitutions, and any withdrawals trigger taxable events. This is the main reason to hold positions long-term and avoid high-turnover funds in taxable accounts.

3. Final liquidation tax When you ultimately sell appreciated assets in a taxable account, you owe capital gains tax on the entire appreciation — including the portion that was generated by reinvested dividends you already paid tax on. This is double taxation that most investors do not model.

The three pools: a direct comparison

The US tax code effectively creates three pools of money with different after-tax return profiles. Every dollar you invest lives in one of these pools.

Worked example: $10,000 invested for 30 years at 7% gross return

Assumptions: 25% marginal ordinary income rate, 15% long-term capital gains rate, 1.5% annual dividend yield.

Roth IRA: $10,000 × (1.07)^30 = $76,123. No tax on withdrawal. After-tax value: $76,123

Traditional 401k (pre-tax contribution): The $10,000 contribution saves $2,500 in taxes today. The full $10,000 grows to $76,123, but you pay ordinary income tax on withdrawal. At 25% rate on withdrawal: $76,123 × 0.75 = $57,092. Add back the $2,500 you saved upfront (invested elsewhere, also growing): complicated. After-tax value: ~$57,092–$65,000 depending on investment of tax savings

Note: Traditional wins over Roth if your withdrawal tax rate is lower than your contribution tax rate. Roth wins if equal or higher. For most high earners at peak income, traditional wins today — but the advantage narrows as retirement income rises.

Taxable account (index ETF, 1.5% yield, 15% dividend tax): Annual drag: 1.5% × 15% = 0.225% per year. Effective return: ~6.775%. $10,000 × (1.06775)^30 = $70,456 pre-liquidation tax. Assuming cost basis of $10,000, gain of $60,456 taxed at 15%: tax = $9,068. After-tax value: ~$61,388

Taxable account (high-dividend fund, 3.5% yield, 37% ordinary income rate): Annual drag: 3.5% × 37% = 1.295% per year. Effective return: ~5.705%. $10,000 × (1.05705)^30 = $51,836 pre-liquidation tax. Gain of $41,836 taxed at 15% (if held long-term): tax = $6,275. After-tax value: ~$45,561

Summary

The difference between the best and worst case is $30,562 on a $10,000 original investment. On a $500,000 portfolio, it is $1.5 million.

After-tax return: the correct formula

To compare any two investments on equal footing, you need the after-tax return, not the gross return.

For a taxable account, approximate after-tax return:

After-tax return ≈ gross return
  − (dividend yield × dividend tax rate)
  − (turnover × average gain × capital gains rate)
  − (expense ratio)

Example: Vanguard Total Stock Market ETF (VTI) in a taxable account

• Gross return (historical): ~7% annualized
• Dividend yield: ~1.3%
• Dividend tax rate (qualified): 15%
• Turnover: ~3% (very low)
• Expense ratio: 0.03%

After-tax return ≈ 7% − (1.3% × 15%) − (3% × ~10% gain × 15%) − 0.03% ≈ 7% − 0.195% − 0.045% − 0.03% ≈ 6.73%

This is why broad index ETFs are already highly tax-efficient in taxable accounts. The drag is minimal. Compare this to an actively managed fund with 80% annual turnover and a 2% dividend yield, held in the same taxable account:

After-tax return ≈ 8% gross − (2% × 35%) − (80% × ~15% gain × 20%) − 1.0% (expense ratio) ≈ 8% − 0.70% − 2.40% − 1.0% ≈ 3.90%

The actively managed fund needs to generate 8% gross just to match the index ETF’s 6.73% after-tax. After fees and taxes, it is not even close.

The benchmark question

Every investment decision should be benchmarked against the after-tax return of the simplest alternative: a total market index ETF held in the most tax-advantaged account available.

For most high-income investors, the after-tax benchmark for new money is approximately:

• In a Roth or 401k: 7–8% gross return, untaxed at growth
• In a taxable account with index ETFs: 6.5–7% after annual drag, LTCG on exit

Any alternative investment — real estate, private equity, alternative funds, complex strategies — needs to beat this benchmark on an after-tax, risk-adjusted, liquidity-adjusted basis. Most do not.

This is not pessimism about alternatives. It is the correct framing. A rental property that generates an 8% gross cash-on-cash return sounds impressive. After vacancy, maintenance, property management, depreciation recapture on sale, and the illiquidity premium you should demand, the after-tax comparison to a Roth compounding at 7% untaxed is much closer than it first appears.

Why this matters for every financial decision

Real estate: Depreciation creates a paper loss but does not change the pre-tax economics. Run the after-tax return including depreciation recapture and compare to the index alternative.

RSUs: Holding employer stock at a concentrated position is a hold decision at the current price. The after-tax return on concentration must beat the diversified index alternative — accounting for single-stock risk.

Tax-loss harvesting: The benefit is the time value of the deferred tax. Calculate the after-tax compound return with and without harvesting before deciding whether the complexity is worth it.

Fund selection: The difference between a 0.03% expense ratio ETF and a 1.0% actively managed fund, held in a taxable account for 30 years, is not 0.97% annually. It is the compounded after-tax drag on that 0.97% — materially larger over long horizons.

Roth conversions: A Roth conversion is a bet that your future tax rate will equal or exceed your current rate. The after-tax math of that bet changes at different conversion amounts, income levels, and time horizons.

Risks and caveats

• Tax rates change. The calculations above use current rates. Future rate changes — up or down — alter the Roth vs traditional calculus. This is a genuine uncertainty.
• State taxes. All examples use federal rates. State income taxes (which do not always follow federal capital gains treatment) can meaningfully change the numbers.
• These are averages. Actual ETF tax drag depends on the fund’s specific turnover, capital gain distributions, and your holding behavior. Funds that issue large capital gain distributions in a given year can dramatically increase taxable account drag.
• Roth conversion timing. The optimal Roth conversion strategy depends on projected retirement income, RMD exposure, state taxes, and estate planning goals — not just the marginal rate comparison.

What most content gets wrong

“Just invest in index funds and you will be fine.” True in direction, incomplete in application. Where you hold the index funds matters as much as which ones you hold. An S&P 500 fund in a taxable account has a different after-tax return than the same fund in a Roth IRA. The fund selection is only half the decision.

“Traditional IRA always beats Roth at high income.” This depends entirely on retirement income and tax rates. High earners who build large traditional IRA balances face Required Minimum Distributions that push them into high brackets in retirement. For many, the Roth becomes the better vehicle precisely because of their future tax exposure — not despite it.

“The expense ratio is all that matters.” Expense ratio is one drag. For taxable accounts, tax drag from distributions is often larger than the expense ratio and is invisible on fund marketing materials.

Decision checklist

Before evaluating any investment or financial strategy, answer:

• What is the gross return?
• What is the after-tax return accounting for annual distributions, turnover, and exit taxes?
• In which account will this be held? Does that change the after-tax outcome?
• What is the after-tax return of the index benchmark in the same account?
• Does this investment beat the benchmark after tax, after fees, after liquidity discount, after complexity cost?
• Am I comparing apples to apples — same time horizon, same risk level, same liquidity?

If you cannot answer these questions for an investment, you do not have enough information to evaluate it.

When to call a CPA

The concepts here are universal. But specific decisions — Roth conversion amounts, optimal asset location across a complex portfolio, depreciation recapture modeling on real estate exits — require your actual numbers. The math is the same; the inputs are yours.

Sources

• IRS Publication 550 — Investment Income and Expenses
• IRC §1222 — Definition of long-term capital gain
• IRC §1(h) — Maximum capital gains rates
• IRC §72 — Taxation of annuities and retirement account distributions
• IRC §408A — Roth IRAs
• IRS Revenue Procedure 2024-40 — Retirement plan contribution limits