Index Investing & Tax-Advantaged Accounts

The thesis. After costs, the average actively managed dollar must underperform the market average — it is the market minus fees (Sharpe's "arithmetic of active management"). SPIVA data consistently shows ~85–90% of US large-cap active funds trail the S&P 500 over 15 years. So: own the whole market at minimal cost and stop guessing.

• Index fund: a fund that mechanically holds every security in an index (e.g., S&P 500, total US market). No manager picking winners → near-zero fees.
• Expense ratio: annual fee as % of assets. Realistic floor today: 0.03% (VOO/VTI, FXAIX, SWPPX) — i.e. $3/yr per $10,000. Anything over ~0.20% for a broad index fund is overpriced. A 1% fee compounds to roughly a quarter of your ending balance over 40 years.
• ETF vs. mutual fund: ETFs trade intraday and are usually more tax-efficient in taxable accounts (in-kind creation/redemption avoids capital-gains distributions). Index mutual funds allow automatic fractional dollar investing. In a 401(k)/IRA the difference is cosmetic.
• Total return: S&P 500 long-run average ≈ ~10% nominal / ~6.5–7% real (1926–present). Wide dispersion: any given year is rarely "average." Don't extrapolate a single decade.

Expense ratios verified from issuer pages as of mid-2026; they change rarely but tag-check before quoting exact basis points.

*Roth tax-free on earnings requires the account be open 5 years and age 59½ (or death/disability/first-home $10k).

• HSA = the only triple-tax-advantaged account: deductible in, grows tax-free, tax-free out for qualified medical. Pay current medical out of pocket, save receipts, and let the HSA compound as a stealth retirement account — there's no deadline to reimburse yourself.
• Backdoor Roth IRA: over the income limit? Contribute non-deductible to a Traditional IRA, then convert to Roth. Watch the pro-rata rule — pre-tax IRA balances make the conversion partly taxable (Form 8606).
• Mega-backdoor Roth: if your plan allows after-tax (non-Roth) 401(k) contributions + in-plan Roth conversion, you can stuff up to the $72,000 total-additions cap minus deferrals and match into Roth. Plan-dependent.
• Roth conversion ladder (early retirement): convert Traditional → Roth in low-income years; each conversion is penalty-free to withdraw after 5 years — the classic FIRE bridge before 59½.
• Rule of 55: leave your employer in or after the year you turn 55 and you can tap that 401(k) penalty-free (not IRAs).
• 72(t) / SEPP: substantially equal periodic payments let you tap an IRA early without the 10% penalty — rigid, locked for 5 years or to 59½.

Roth IRA — contribution phase-out (MAGI, 2026)

Traditional IRA — deduction phase-out (MAGI, 2026, if covered by a workplace plan)

HSA & HDHP (2026, Rev. Proc. 2025-19)

Long-term capital-gains brackets (2026 taxable income)

Net investment income tax (NIIT) of 3.8% stacks on top above $200k single / $250k MFJ MAGI. Short-term gains (held ≤1 year) are taxed as ordinary income — hold >1 year.

Year-by-year change (2025 → 2026)

Same dollars, different tax drag depending on where you hold each asset. The principle: put tax-inefficient assets in shelters, tax-efficient assets in taxable.

• One-fund simplicity beats perfect location. If juggling locations stops you from investing, a single target-date or total-world fund in every account is a fine choice — behavior > optimization.
• Hold international in taxable to claim the foreign tax credit (lost inside an IRA).
• Never hold bonds in a Roth if you have tax-deferred space — you're wasting your most valuable (tax-free) real estate on a low-growth asset.

• The 4% rule (Bengen / Trinity study): withdraw 4% of the initial portfolio, adjust for inflation yearly; historically survived 30 years in ~95%+ of US scenarios. It's a planning heuristic, not a guarantee — sequence-of-returns risk early in retirement is the real danger. Longer horizons (FIRE at 40) lean toward 3.25–3.5%.
• Withdrawal order (typical tax-minimizing default): taxable first → tax-deferred (Traditional) next → Roth last. But blend: realize some Traditional income each year up to the top of a low bracket (and do Roth conversions) so you don't get RMD-bombed at 73.
• RMDs (Required Minimum Distributions): begin at age 73 (rising to 75 for those born 1960+) on Traditional 401(k)/IRA. Roth IRAs never have RMDs; Roth 401(k)s no longer have them (SECURE 2.0, 2024+). Miss one and the penalty is 25% (10% if corrected promptly).
• QCD (Qualified Charitable Distribution): from 70½, send up to $108,000 (2025, inflation-indexed) of IRA money directly to charity — satisfies RMDs and stays off your AGI.
• Capital-gains harvesting: in low-income years, realize gains up to the top of the 0% LTCG bracket ($98,900 MFJ taxable income in 2026) to reset basis tax-free.

QCD figure is the 2025 indexed amount; the 2026 number tracks inflation — verify before quoting.

• What it is: sell a position at a loss to bank a capital loss, immediately buy a similar-but-not-identical fund to stay invested. The loss offsets gains and up to $3,000/yr of ordinary income; the rest carries forward forever.
• Wash-sale rule (IRC §1091): the loss is disallowed if you buy a substantially identical security within 30 days before or after the sale — across all your accounts, including your spouse's and your IRA. The 61-day window is the danger zone.
• "Substantially identical" is the art: selling VOO (S&P 500) and buying VTI (total market) is broadly considered safe; selling VOO and buying IVV (another S&P 500 fund) is risky. Use a different index or provider.
• IRA trap: a replacement buy inside your IRA permanently kills the loss (Rev. Rul. 2008-5) — basis is not restored. Turn off auto-reinvest/auto-buy in retirement accounts while harvesting.
• Tax-rate arbitrage: you harvest a short-or-long-term loss now but it offsets future gains. Best when you offset short-term gains (taxed at ordinary rates) or income. Watch out for resetting basis lower → larger gains later (deferral, not free money — unless you get a step-up at death).
• Don't let the tax tail wag the dog: a tiny loss isn't worth churning; harvesting matters most in volatile down markets and for large taxable balances. Useless inside tax-advantaged accounts (no taxable gains to offset).

Worked example: You bought $50k of VTI; it drops to $42k. Sell (bank an $8k loss), buy $42k of VXUS-heavy total-world or VOO same day. Use $3k against this year's salary, carry $5k forward. You stayed ~100% invested and pocketed a tax asset.

• Leaving the match on the table. Not contributing enough to get the full employer match is a guaranteed 50–100% instant return refused. Always fund to the match first.
• Cash drag in the IRA. Contributing to an IRA but never buying funds — the money sits in a settlement account earning nothing. Contributing ≠ investing.
• Performance-chasing & stock-picking. Last year's winner is a coin flip next year. The index already owns it.
• Timing the market. Missing the 10 best days over 20 years roughly halves your return; those days cluster next to the worst ones. Time in > timing.
• High expense ratios & loads. A 1% advisor fee + 0.75% fund fee can consume ~40% of your lifetime gains. Insist on low-cost index funds; avoid front-loaded funds entirely.
• Selling in a crash. The single most expensive behavioral error. Write an Investment Policy Statement and automate contributions so you keep buying when it's cheap.
• Backdoor Roth pro-rata surprise. Doing a backdoor Roth while holding a big pre-tax IRA → the conversion is mostly taxable. Roll the pre-tax IRA into a 401(k) first.
• Ignoring the HSA. Treating the HSA as a spending account instead of the best retirement vehicle in the code. Invest it; pay current medical from cash flow.
• Over-diversifying into overlap. Owning five "different" funds that are all 80% the same megacaps. Two or three broad funds is plenty.
• Home-country / single-stock concentration. 100% one country or piling into your employer's stock concentrates risk exactly where your paycheck already is.

1. Build a 1-month emergency buffer + pay off any >8% debt before investing.
2. Contribute to the 401(k) up to the full match (free money).
3. Max the HSA if you have an HDHP (triple tax-free; invest it).
4. Max a Roth or Traditional IRA ($7,500). Backdoor if over the income limit.
5. Finish maxing the 401(k) ($24,500 total deferral).
6. Mega-backdoor Roth if available, then taxable brokerage — unlimited, flexible.
7. Buy broad, cheap index funds (US + international + bonds), set an age-appropriate split, automate, and ignore the noise for 30 years.