401(k) Retirement Calculator

A 401(k) is an employer-sponsored retirement account that grew out of the Revenue Act of 1978. It takes its name from Section 401(k) of the Internal Revenue Code. The 401(k) provides three major benefits: tax-deferred growth, employer matching (free money), and high annual contribution limits. **Formula Derivation**: Future value of a growing annuity plus existing balance: FV = P × (1 + r)^n + PMT × [((1 + r)^n - 1) / r] Where: - P = Current balance (principal) - PMT = Annual contribution - r = Annual return (decimal) - n = Years until retirement **Contribution Limits (2024)**: - **Employee**: $23,000/year ($30,500 if 50+) - **Total (employee + employer)**: $69,000/year ($76,500 if 50+) - **Highly compensated**: Additional limits may apply These limits increase each year with inflation. **Types of 401(k)s**: 1. **Traditional 401(k)**: Contributions reduce current taxable income; taxes paid on withdrawal in retirement. Best if you expect lower tax bracket in retirement. 2. **Roth 401(k)**: Contributions made with after-tax money; tax-free withdrawals in retirement. Best if you expect higher tax bracket in retirement or want tax-free growth. 3. **SIMPLE 401(k)**: For small businesses; lower limits but simpler. 4. **Safe Harbor 401(k)**: Mandatory employer contributions in exchange for simpler compliance. **Employer Matching**: Most common matches: - **100% match up to 3%** of salary ($1:$1 up to limit) - **50% match up to 6%** of salary ($0.50 per $1 up to limit) - **Tiered matches** (common for larger employers) **ALWAYS contribute at least enough to get the full match — it's free money. Missing the match is like refusing a raise.** **Vesting**: Employer contributions are often 'vested' gradually. Common schedules: - **Immediate vesting**: You own employer contributions immediately - **Cliff vesting**: 0% vested until a specific date (often 3 years), then 100% - **Graded vesting**: 20% per year for 5 years Your own contributions are ALWAYS 100% vested immediately. **Investment Options**: Most 401(k)s offer: - **Target-date funds**: Automatically rebalance as you age (most common default) - **Index funds**: Low-cost, track market benchmarks - **Actively managed funds**: Higher fees, rarely beat indices - **Company stock**: Risk of 'Enron scenario' — diversify! - **Bond funds**: Lower risk, lower return **Historical Market Returns**: - Stock market (S&P 500): ~10% average annual nominal return, ~7% real (inflation-adjusted) - Bonds: ~4-5% nominal - Mixed portfolio (60/40): ~8% nominal, ~5% real Use conservative estimates (6-7%) for planning. **The Power of Compound Interest**: A 25-year-old contributing $5,000/year until age 65 with 7% returns: - Total contributed: $200,000 (40 years) - Final balance: ~$998,000 - Growth beyond contributions: ~$800,000 (4x the original investment) Starting at 35 with same $5,000/year: - Total contributed: $150,000 (30 years) - Final balance: ~$472,000 - Growth: ~$322,000 The 10-year head start nearly DOUBLES the final amount. This is why starting early matters more than contributing more later. **Withdrawal Rules**: - **Before age 59½**: 10% penalty + income tax (with exceptions) - **After age 59½**: Just income tax on Traditional; tax-free on Roth - **Required Minimum Distributions (RMDs)**: Traditional 401(k) requires withdrawals starting at 73 (SECURE Act 2.0) - **Hardship withdrawals**: Allowed for specific circumstances with penalty