tax-efficiency - SKILL.md Agent Skill

name: tax-efficiency description: "Maximizes after-tax returns through strategic asset location, gain/loss management, and withdrawal sequencing. Use when the user asks about asset location, Roth conversions, tax-efficient withdrawals, tax lot selection, or charitable giving with appreciated securities. Also trigger when users mention 'which account should I hold bonds in', 'tax drag', 'Roth vs Traditional', 'RMD planning', 'bracket stuffing', 'HIFO vs FIFO', or ask how to minimize taxes on investments. For tax-loss harvesting execution and wash-sale mechanics, see the tax-loss-harvesting skill."

Tax-Efficient Investing

Core Concepts

Asset Location

Place tax-inefficient assets in tax-advantaged accounts and tax-efficient assets in taxable accounts:

Tax-deferred accounts (Traditional IRA, 401k): Bonds, REITs, high-turnover funds, TIPS — assets generating ordinary income
Tax-exempt accounts (Roth IRA, Roth 401k): Highest expected growth assets — all growth is permanently tax-free
Taxable accounts: Index equity funds (low turnover, qualified dividends, tax-loss harvesting eligible), municipal bonds, tax-managed funds

The benefit of asset location increases with the spread between ordinary income tax rates and capital gains rates, and with the size of the tax-advantaged accounts relative to total portfolio.

Tax-Loss Harvesting (TLH)

Realize investment losses to offset capital gains, reducing current tax liability while maintaining market exposure:

Sell a losing position, immediately buy a similar (but not "substantially identical") replacement
Harvested losses offset gains dollar-for-dollar; net losses offset up to $3,000 of ordinary income per year; excess carries forward indefinitely
Wash-sale rule (30 days): Cannot repurchase the same or substantially identical security within 30 days before or after the sale — applies across all accounts (including spouse's accounts and IRAs)
Tax alpha from TLH: Estimated 0.5-1.5% per year in early years of a portfolio's life, declining as cost basis rises
Best opportunities arise during market volatility and in the first few years of investing

After-Tax Return

Different income types face different tax rates:

Interest income: Taxed at ordinary income rates
Qualified dividends: Taxed at long-term capital gains rates (0%, 15%, or 20% + 3.8% NIIT)
Short-term capital gains (held ≤ 1 year): Ordinary income rates
Long-term capital gains (held > 1 year): Preferential rates (0%, 15%, or 20% + 3.8% NIIT)
The 3.8% NIIT applies above $250,000 MAGI (MFJ) — a statutory threshold that is not inflation-indexed
After-tax return on income: R_at = R × (1 - t)
Capital gains are taxed only at realization, providing a deferral benefit

Tax Drag

The annual cost of taxes on investment returns:

Tax drag = pre-tax return - after-tax return
High-turnover funds generate more short-term gains → higher tax drag
Index funds with low turnover minimize tax drag
ETFs generally more tax-efficient than mutual funds (in-kind creation/redemption process)

Tax Lot Management

When selling partial positions, the method of selecting which lots to sell affects tax liability:

Specific identification: Choose exactly which lots to sell
HIFO (Highest In, First Out): Sell highest-cost-basis lots first to minimize gains
FIFO (First In, First Out): Default method; may realize larger gains on older lots
Tax-optimal: Select lots to minimize current-year tax liability considering holding period and gains/losses

Roth Conversion

Convert Traditional IRA/401k assets to Roth, paying ordinary income tax now for tax-free growth and withdrawals later:

Breakeven analysis: Conversion is beneficial if current marginal tax rate < expected future marginal tax rate
Factors favoring conversion: Long time horizon, low current income year, expectation of higher future rates, desire to reduce future RMDs, estate planning benefits
Partial conversions: Convert just enough to fill current tax bracket ("bracket stuffing")
Tax on conversion: conversion amount × current marginal rate

Required Minimum Distributions (RMDs)

Mandatory annual withdrawals from tax-deferred accounts (Traditional IRA, 401k) beginning at age 73 (under SECURE 2.0, rising to 75 in 2033):

RMD = account balance (Dec 31 prior year) / distribution period (from IRS Uniform Lifetime Table)
Failure penalty: 25% excise tax on shortfall (reduced from prior 50%)
RMDs are taxed as ordinary income and can push retirees into higher brackets
Roth IRAs have no RMDs during the owner's lifetime

Withdrawal Sequencing

The order of withdrawals from different account types in retirement:

General rule: Taxable → Tax-deferred → Roth (preserves tax-free growth longest)
Optimized approach: Withdraw from taxable first, then fill low tax brackets with tax-deferred withdrawals, use Roth to avoid bracket jumps
Dynamic strategy: Adjust each year based on income, deductions, and bracket thresholds

Charitable Giving Strategies

Donate appreciated stock: Avoid capital gains tax and deduct full fair market value (must be held > 1 year)
Qualified Charitable Distributions (QCDs): Donate up to $111,000/year (2026 limit, indexed annually) directly from IRA to charity (counts toward RMD, excluded from taxable income); available at age 70½+
Donor-Advised Funds (DAFs): Bunch multiple years of donations for itemized deduction, invest tax-free, distribute to charities over time

Key Formulas

Formula	Expression	Use Case
After-tax return (income)	R_at = R × (1 - t)	Bond/interest income after tax
After-tax return (deferred gains)	R_at = ((1 + R)^n × (1 - t_cg) + t_cg)^(1/n) - 1	Unrealized equity with deferral benefit
Tax-loss harvesting value	TLH_value = loss × marginal_tax_rate	Immediate tax benefit of harvesting
Roth conversion breakeven	t_now < t_future	Convert when current rate < future rate
RMD amount	RMD = balance_Dec31 / distribution_period	Required minimum distribution
Appreciated-stock donation benefit	Tax saved = FMV × t_income + gain × t_cg_avoided	Tax benefit of donating appreciated stock (deduction + avoided gains tax)

Worked Examples

Example 1: Asset location optimization

Given: $500K in taxable brokerage + $500K in Traditional IRA. Portfolio target: 50% bonds (yielding 5%) and 50% equities (expected 10% total return, 2% qualified dividends). Marginal tax rate: 32% ordinary, 15% LTCG. Calculate: Optimal asset placement and annual tax savings vs naive allocation. Solution:

Optimal placement: Bonds ($500K) in IRA; Equities ($500K) in taxable.
Naive placement (50/50 each): Taxable has $250K bonds + $250K equities; IRA has $250K bonds + $250K equities.
Tax drag — naive: Taxable bonds: $250K × 5% × 32% = $4,000. Taxable equity dividends: $250K × 2% × 15% = $750. Total tax = $4,750.
Tax drag — optimal: Taxable equity dividends only: $500K × 2% × 15% = $1,500. Total tax = $1,500.
Annual tax savings: $4,750 - $1,500 = $3,250/year (0.325% of total portfolio).
Over 20 years compounded, this adds significantly to after-tax wealth.

Example 2: Roth conversion breakeven

Given: Consider converting $50,000 from Traditional IRA to Roth. Current marginal tax rate: 24%. Tax on conversion paid from outside funds. Investment horizon: 20 years. Expected return: 7%. Simplifying assumption: Assume the $12,000, if not used for conversion tax, would grow at the same 7% with no tax drag — i.e., side-fund growth itself is untaxed. Calculate: Future marginal tax rate at which conversion breaks even. Solution:

Cost of conversion now: $50,000 × 24% = $12,000 tax paid today.
Traditional IRA path: $50,000 grows to $50,000 × (1.07)^20 = $193,484. After-tax at withdrawal: $193,484 × (1 - t_future).
Roth path: $50,000 grows to $193,484 tax-free, but the $12,000 side fund forgoes growth to $12,000 × (1.07)^20 = $46,436. Roth net value: $193,484 - $46,436 = $147,048.
Breakeven: Set Traditional after-tax = Roth net value. $193,484 × (1 - t_future) = $193,484 - $46,436 → t_future = $46,436 / $193,484 = 24.0%.
Conclusion: Under this simplification the breakeven future rate equals the current rate (24%) — both sides scale by the same (1.07)^20, so the horizon and return cancel. In reality the taxable side fund suffers tax drag on its dividends and realized gains, so paying conversion tax from outside funds tilts the comparison toward Roth even when the future rate merely equals the current rate.

Common Pitfalls

TLH wash sale violations, including purchases in other accounts, IRAs, or a spouse's account within the 30-day window
Over-harvesting losses that defer gains to higher tax brackets later (basis step-down compounds)
Not considering state taxes in asset location decisions — state tax treatment varies significantly
Ignoring the tax benefit of donating appreciated securities vs cash (avoids capital gains and gets full deduction)
RMD-driven forced selling at inopportune times — plan withdrawals ahead of deadlines
Roth converting too aggressively and pushing into a higher bracket in the conversion year
Forgetting the 3.8% Net Investment Income Tax (NIIT) above $250,000 MAGI (MFJ) — a statutory threshold that is not inflation-indexed, so it captures more taxpayers each year
Not coordinating tax strategy across spouses' accounts

Cross-References

investment-policy (wealth-management plugin, Layer 5): Tax constraint in IPS governs asset location and turnover management
performance-attribution (wealth-management plugin, Layer 5): After-tax return attribution requires tax-aware calculations
debt-management (wealth-management plugin, Layer 6): Mortgage interest deductibility interacts with tax planning
savings-goals (wealth-management plugin, Layer 6): Account type selection (Roth vs Traditional) is a core tax decision
liquidity-management (wealth-management plugin, Layer 6): Tax implications of accessing different account types affect liquidity planning
tax-loss-harvesting (wealth-management plugin, Layer 5): dedicated TLH workflow skill with detailed candidate identification, wash-sale tracking, and execution planning
financial-planning-workflow (advisory-practice plugin, Layer 10): tax-aware strategies are core recommendations in comprehensive financial plans

Running the script

Run with uv run scripts/tax_efficiency.py (the PEP 723 header resolves dependencies automatically) or with python3 scripts/tax_efficiency.py after pip install numpy scipy. The bare run prints a demo covering after-tax returns, tax drag, TLH benefit, asset location placement, and Roth conversion breakeven. Pass --verify to assert the demo outputs match this skill's worked examples (prints PASS/FAIL), or --help for an overview of the available classes. The file is primarily meant to be imported as a module (e.g., from tax_efficiency import AfterTaxReturn, AssetLocation, BreakevenAnalysis).