US Retirement Accounts

Retirement saving in the United States relies heavily on tax-advantaged accounts — the government gives up tax revenue today to encourage people to save for a future when they can no longer earn a paycheck. Understanding how each account works, how they interact, and how to sequence contributions between them is one of the highest-return decisions in personal finance, often worth more than any individual stock pick.

Learning Objectives

By the end of this topic, you should be able to:

• Explain how pre-tax (Traditional) and after-tax (Roth) contributions differ for both 401(k)s and IRAs
• Calculate the value of an employer 401(k) match and explain why leaving it unclaimed is lost compensation
• State the 2024 IRS contribution limits for 401(k)s, IRAs, and catch-up contributions
• Describe how Required Minimum Distributions (RMDs) work and which accounts are exempt
• Compare Traditional vs. Roth accounts and recommend one based on expected future tax bracket
• Explain the backdoor Roth IRA strategy and why high earners use it
• Sequence retirement contributions in the order most personal finance experts recommend

Quick Answer

The US retirement system rests on three legs: Social Security, employer-sponsored plans (mainly the 401(k)), and individual accounts (IRAs). A 401(k) lets you contribute up to $23,000 in 2024 (pre-tax or Roth) directly from your paycheck, often with an employer match that is effectively free money. IRAs are opened independently and cap contributions at $7,000 in 2024. Traditional accounts give you a tax deduction now and tax the withdrawals later; Roth accounts tax you now but let qualified withdrawals grow completely tax-free. Most experts recommend contributing enough to capture the full 401(k) match first, then maxing a Roth IRA, then returning to max the 401(k) — because employer matching is a guaranteed return no investment can reliably beat.

The Retirement Savings Landscape

Unlike many countries, the US does not have a universal mandatory pension for private-sector workers. Instead, the system has three "legs":

1. Social Security — a federal defined-benefit program funded by payroll taxes; provides a base income in retirement
2. Employer-sponsored plans — primarily 401(k) plans; defined-contribution accounts where you and your employer contribute
3. Individual accounts — IRAs (Individual Retirement Accounts) that you open independently

Each leg has a different failure mode: Social Security alone typically replaces only about 40% of pre-retirement income for an average earner, so relying on it exclusively means a large drop in living standards. This is why the employer plan and individual accounts exist to fill the gap.

401(k) Plans

A 401(k) is an employer-sponsored retirement savings plan. The name comes from the section of the Internal Revenue Code that created it (§ 401(k)). Contributions are deducted automatically from your paycheck, which removes the temptation to skip saving in a given month.

How It Works

• Pre-tax contributions (Traditional 401(k)): Contributions reduce your taxable income today; withdrawals in retirement are taxed as ordinary income
• After-tax contributions (Roth 401(k)): Contributions come from after-tax dollars; withdrawals in retirement (including earnings) are tax-free
• Investments grow tax-deferred (Traditional) or tax-free (Roth) inside the account — you owe no capital gains tax on trades made inside the account

Example: Priya earns $80,000 and contributes 10% ($8,000) to a Traditional 401(k). Her taxable income for the year drops to $72,000, saving roughly $1,760 in federal tax at a 22% marginal rate. If she had used a Roth 401(k) instead, her taxable income would stay at $80,000, but every dollar of the $8,000 — plus all future growth — comes out tax-free in retirement.

2024 Contribution Limits

Category	Limit
Employee contribution limit	$23,000
Catch-up contribution (age 50+)	Additional $7,500 (total $30,500)
Total limit (employee + employer)	$69,000 (or 100% of compensation, whichever is less)

Employer Match — Free Money

Most employers match a portion of your 401(k) contributions — e.g., "50% match on the first 6% of salary":

If you earn $60,000 and contribute 6% ($3,600), your employer adds 50% of that = $1,800 free. That's an instant 50% return before any investment growth, something no brokerage account can match.

Always contribute at least enough to get the full employer match. Not doing so is leaving guaranteed compensation on the table — equivalent to declining part of your salary.

Vesting Schedule

Employer match contributions may be subject to a vesting schedule — you don't "own" the match until you've worked there long enough:

• Cliff vesting: e.g., 0% vested until year 3, then 100% immediately
• Graded vesting: e.g., 20% per year over 5 years

Your own contributions are always 100% vested immediately; only the employer's matching dollars can be subject to vesting.

Withdrawal Rules

• Normal retirement age: 59½ — withdrawals allowed without penalty
• Early withdrawal: Before 59½, you pay income tax + 10% penalty (with exceptions: disability, substantially equal periodic payments (SEPP), separation from service at age 55+, hardship)
• Required Minimum Distributions (RMDs): Must begin by age 73 (per SECURE 2.0 Act, 2022) for Traditional 401(k)s; Roth 401(k)s no longer have RMDs (as of 2024)

Why RMDs exist: The government allowed Traditional accounts to grow tax-deferred, but it still wants to collect income tax eventually. RMDs force withdrawals — and taxation — starting at age 73, calculated by dividing the account balance by an IRS life-expectancy factor. Failing to withdraw the required amount triggers a steep excise tax penalty (25% of the shortfall, reduced to 10% if corrected quickly).

Individual Retirement Accounts (IRAs)

IRAs are retirement accounts you open independently at a brokerage (Fidelity, Vanguard, Schwab, etc.), regardless of your employer. Anyone with earned income can open one.

Traditional IRA

• Contributions: May be tax-deductible (depending on income and whether you have an employer plan)
• Growth: Tax-deferred
• Withdrawals: Taxed as ordinary income in retirement
• 2024 contribution limit: $7,000 ($8,000 if age 50+)
• Deductibility phase-out (if covered by workplace plan, single filer): Starts at $77,000 MAGI, fully phased out at $87,000
• RMDs: Required starting at age 73, same as a Traditional 401(k)

Roth IRA

The Roth IRA is widely considered the best retirement account available to most Americans who qualify.

• Contributions: After-tax (no deduction)
• Growth: Tax-free
• Qualified withdrawals: Completely tax-free (contributions can be withdrawn any time, earnings after age 59½ and 5-year holding period)
• No RMDs: Never required to take distributions during the owner's lifetime
• 2024 contribution limit: $7,000 ($8,000 if age 50+)
• Income limits (2024): Phase-out begins at $146,000 MAGI (single) / $230,000 (married filing jointly); completely phased out at $161,000 / $240,000

Real-world example: Marcus, age 25, contributes $7,000/year to a Roth IRA and earns an average 8% annual return. By age 65, that account holds roughly $1.95 million — and every dollar of it, including nearly $1.7 million in growth, comes out completely tax-free. A Traditional account with the identical contributions and growth would owe ordinary income tax on the entire withdrawal.

Roth IRA vs. Traditional IRA — which to choose?

Situation	Better choice
You expect to be in a higher tax bracket in retirement	Roth (pay taxes now at lower rate)
You expect to be in a lower tax bracket in retirement	Traditional (defer taxes to when rate is lower)
You're young with a long time horizon	Roth (decades of tax-free compound growth)
You need to reduce taxable income now	Traditional
You're unsure	Contribute to both; diversify tax treatment

Backdoor Roth IRA

High earners above the Roth IRA income limit can use the backdoor Roth strategy:

1. Contribute to a non-deductible Traditional IRA (no income limit)
2. Immediately convert it to a Roth IRA
3. Pay taxes only on any gains (minimal if done immediately)

This is legal and widely used. Note the pro-rata rule: if you have other pre-tax IRA money, the conversion will be partially taxable proportional to pre-tax funds — so the strategy works most cleanly for people with no existing Traditional IRA balance.

Self-Employed Retirement Accounts

Account	2024 Limit	Best for
SEP-IRA	25% of net self-employment income, up to $69,000	Simple; ideal for sole proprietors
Solo 401(k)	$23,000 employee + up to $46,000 employer = $69,000 total	Higher limits; good for high-income self-employed
SIMPLE IRA	$16,000 ($19,500 catch-up)	Small businesses with employees

Social Security

Social Security (administered by the Social Security Administration, SSA) is a federal program that provides retirement, disability, and survivor benefits. It is funded by payroll taxes — 6.2% from employee + 6.2% from employer on wages up to the Social Security wage base ($168,600 in 2024). Self-employed pay both sides (12.4% total, but deduct half).

Eligibility

• You need 40 work credits (roughly 10 years of work) to qualify for retirement benefits
• Credits are earned by earning income — up to 4 credits per year

Benefit Calculation

Your benefit is based on your 35 highest-earning years of indexed wages (called the AIME — Average Indexed Monthly Earnings). The SSA then applies a progressive formula (the PIA — Primary Insurance Amount) to calculate your monthly benefit. Because the formula uses your best 35 years, working fewer than 35 years means zeros are averaged in, which can meaningfully lower your benefit.

When to Claim

Age	Effect on benefit
62	Earliest you can claim; benefit reduced by up to 30% permanently
67 (born 1960+)	Full Retirement Age (FRA) — 100% of PIA
70	Maximum benefit — 8% higher per year than FRA for each year you delay

Break-even analysis: Claiming at 70 vs. 62 takes roughly 12–13 years of higher payments to recoup the missed early payments. If you expect to live past ~80, delaying often pays off significantly.

Social Security and Taxes

Up to 85% of Social Security benefits can be subject to federal income tax if your "combined income" (AGI + non-taxable interest + half of Social Security) exceeds:

• $25,000 (single) / $32,000 (married filing jointly) — up to 50% taxable
• $34,000 (single) / $44,000 (married) — up to 85% taxable

The Recommended Priority Order

Most personal finance experts recommend this general priority for retirement saving:

1. 401(k) up to employer match — guaranteed return via match
2. Pay off high-interest debt (credit cards > ~6%)
3. Max out HSA (if eligible — triple tax advantage for healthcare)
4. Max out Roth IRA ($7,000)
5. Max out 401(k) (remaining $16,000 to reach $23,000 limit)
6. Taxable brokerage account — for additional investing beyond tax-advantaged space

Key Terms

Term	Definition	Related Concept
401(k)	Employer-sponsored retirement plan allowing pre-tax or Roth payroll contributions	Employer match, vesting
IRA	Individual Retirement Account opened independently at a brokerage	Traditional IRA, Roth IRA
MAGI	Modified Adjusted Gross Income — AGI with certain deductions added back; used for eligibility phase-outs	Roth IRA income limits
RMD	Required Minimum Distribution — mandatory withdrawals starting at age 73 for Traditional accounts	Traditional 401(k), Traditional IRA
Vesting	Ownership of employer contributions per the plan schedule	401(k) employer match
Employer Match	Additional contribution an employer makes based on your own 401(k) contribution	Vesting, 401(k)
Backdoor Roth IRA	Strategy of contributing to a non-deductible Traditional IRA then converting to Roth to bypass income limits	Pro-rata rule
Pro-Rata Rule	IRS rule taxing Roth conversions proportionally if pre-tax IRA money exists	Backdoor Roth IRA
Rollover	Moving money from one retirement account to another without tax consequences	Direct rollover, 60-day rollover
Full Retirement Age (FRA)	Age (67 for those born 1960+) at which Social Security pays 100% of the calculated benefit	Social Security claiming age

Common Mistakes

Misconception: You should max out your Roth IRA before contributing anything to your 401(k). Why it's wrong: Skipping the 401(k) means skipping the employer match, which is an immediate, guaranteed return (often 50–100% on the matched dollars) that no other account can replicate. A Roth IRA's tax-free growth is valuable, but it cannot make up for free money left unclaimed. Correct understanding: Contribute enough to your 401(k) to capture the full employer match first, then direct additional savings to a Roth IRA, then return to the 401(k) to contribute further.

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Misconception: A Traditional 401(k)/IRA and a Roth 401(k)/IRA are basically the same thing with different names. Why it's wrong: They differ in when you pay tax and how withdrawals are treated. Traditional accounts defer tax to withdrawal (taxed as ordinary income and subject to RMDs); Roth accounts are funded with after-tax money but grow and withdraw completely tax-free (and Roth IRAs have no RMDs at all). Correct understanding: The choice depends on whether you expect your tax rate to be higher or lower in retirement than it is today — this single assumption drives which account type saves you more money.

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Misconception: Once you leave a job, your 401(k) money is stuck there or you lose it. Why it's wrong: Your own contributions (and any vested employer contributions) are yours to keep regardless of employer. You can roll the balance into your new employer's 401(k) or into an IRA without owing any tax, as long as it's done as a direct rollover. Correct understanding: Use a direct rollover to move an old 401(k) into an IRA or new employer plan; avoid the 60-day rollover method, which risks accidental taxation and penalties if funds aren't redeposited in time.

Comparison and Connections

Feature	Traditional 401(k) / IRA	Roth 401(k) / IRA
Tax on contribution	Pre-tax (reduces taxable income now)	After-tax (no deduction)
Tax on growth	Tax-deferred	Tax-free
Tax on qualified withdrawal	Ordinary income tax	Tax-free
RMDs	Required at age 73	None for Roth IRA; none for Roth 401(k) as of 2024
Income limits	None for contributing (deduction may phase out)	Roth IRA phases out at high income; Roth 401(k) has none
Best for	Expect lower tax bracket in retirement; need deduction now	Expect same/higher tax bracket in retirement; young savers

Practice Questions

Recall

1. What is the 2024 employee contribution limit for a 401(k), and what is the additional catch-up amount for those 50 and older? Answer guidance: $23,000 employee limit; additional $7,500 catch-up for age 50+, bringing the total to $30,500.

2. At what age must Required Minimum Distributions begin for a Traditional 401(k) or Traditional IRA? Answer guidance: Age 73, per the SECURE 2.0 Act (2022). Roth IRAs and Roth 401(k)s (as of 2024) have no RMDs.

Understanding

3. Why is failing to capture a full employer 401(k) match considered "leaving free money on the table"? Answer guidance: The employer match is additional compensation contingent only on your own contribution; not contributing enough to get it means forfeiting guaranteed money that no investment return can reliably replicate.

4. Explain why a young worker with a long time horizon is often advised to prefer a Roth account over a Traditional account. Answer guidance: Contributions are likely taxed at a low current rate, and decades of tax-free compounding growth are never taxed on withdrawal — the earlier the money goes in, the more growth escapes taxation entirely.

Application

5. An employee earns $60,000 and their employer offers 50% match on the first 6% of salary contributed. If the employee contributes only 3% of salary, how much employer match do they receive, and how much are they leaving unclaimed? Answer guidance: 3% of $60,000 = $1,800 contributed; match = 50% × $1,800 = $900. Full match at 6% ($3,600 contributed) would be $1,800; the employee is leaving $900 in match unclaimed.

6. A 28-year-old contributes $7,000/year to a Roth IRA and averages 8% annual returns until age 65. Approximately how much will the account be worth, and how much of that is tax-free growth? Answer guidance: Roughly $1.7-2.0 million total (future value of a 37-year, $7,000/year annuity at 8%); total contributions would be about $259,000, so the remainder - around $1.4–1.7 million — is tax-free investment growth.

Analysis

7. Compare the lifetime tax outcome of a high earner using a Traditional 401(k) throughout their career versus a Roth 401(k), assuming their tax bracket in retirement is meaningfully lower than during their working years. Answer guidance: The Traditional account wins in this scenario — the deduction is taken at a high marginal rate during working years, and withdrawals are taxed later at a lower rate, resulting in a net tax savings compared to paying tax upfront at the higher rate via Roth.

8. A high-income earner is above the Roth IRA income limit but has no existing pre-tax IRA balance. Evaluate whether a backdoor Roth IRA is a good strategy for them and explain why the pro-rata rule matters. Answer guidance: With no existing pre-tax IRA balance, the backdoor Roth is clean — the non-deductible contribution converts to Roth with little to no tax owed on gains. If they had a large pre-tax IRA balance, the pro-rata rule would make a significant portion of the conversion taxable, reducing the strategy's efficiency.

FAQ

Should I contribute to a Roth or Traditional 401(k) if I'm not sure about my future tax bracket? When uncertain, splitting contributions between both is a reasonable hedge — it diversifies your tax exposure so you're not fully dependent on guessing correctly. Many financial advisors also suggest leaning Roth earlier in your career (when your income and tax bracket are typically lower) and shifting toward Traditional as your income and tax bracket rise, since the deduction becomes more valuable at higher marginal rates.

What happens to my 401(k) if I change jobs? Your vested balance is entirely yours. You generally have four options: leave it with the old employer's plan (if allowed), roll it into your new employer's 401(k), roll it into an IRA, or cash it out (not recommended before 59½ due to taxes and the 10% penalty). A direct rollover, where funds move institution-to-institution without passing through your hands, avoids withholding and the risk of missing the 60-day redeposit window.

Can I contribute to both a 401(k) and an IRA in the same year? Yes. The two accounts have separate contribution limits ($23,000 for a 401(k), $7,000 for an IRA in 2024), so you can max out both if you have the income to do so. Having a 401(k) can, however, reduce or eliminate the tax deduction on a Traditional IRA contribution depending on your income.

What is the 10% early withdrawal penalty, and does it always apply? Withdrawing from a Traditional 401(k) or IRA before age 59½ generally triggers ordinary income tax plus a 10% penalty on the withdrawn amount. Exceptions include a first-time home purchase (IRA only, up to $10,000), certain medical expenses, disability, and separation from service at age 55+ for a 401(k). Roth IRA contributions (not earnings) can always be withdrawn tax- and penalty-free since you already paid tax on them.

Is Social Security going to run out before I retire? The Social Security trust fund is projected to be able to pay full benefits only through the mid-2030s under current law; after that, incoming payroll tax revenue alone would cover roughly 80% of promised benefits absent reform. This does not mean the program disappears — historically, Congress has adjusted taxes or benefits before shortfalls hit — but it is a reasonable argument for not relying on Social Security alone for retirement income.

Quick Revision

• Three legs of US retirement: Social Security, employer plans (401(k)), individual accounts (IRA)
• 2024 401(k) limit: $23,000 employee ($30,500 with age-50+ catch-up); combined employer+employee cap $69,000
• 2024 IRA limit: $7,000 ($8,000 if age 50+), shared across Traditional and Roth
• Traditional accounts: tax deduction now, ordinary income tax on withdrawal, RMDs start at age 73
• Roth accounts: no deduction now, completely tax-free qualified withdrawals, no RMDs (IRA always; 401(k) as of 2024)
• Always contribute enough to a 401(k) to get the full employer match — it's an immediate guaranteed return
• Employer match may vest over time (cliff or graded); your own contributions are always fully vested
• Backdoor Roth IRA lets high earners bypass Roth income limits by converting a non-deductible Traditional IRA
• Pro-rata rule taxes backdoor Roth conversions proportionally if other pre-tax IRA money exists
• Early withdrawal before 59½ triggers income tax plus a 10% penalty, with limited exceptions
• Social Security full retirement age is 67 (born 1960+); claiming at 70 maximizes the monthly benefit
• Recommended contribution order: 401(k) to match → high-interest debt → HSA → max Roth IRA → max 401(k) → taxable brokerage

Related Topics

Prerequisites: Understanding of gross vs. take-home pay and marginal tax brackets, basic compound interest, familiarity with how employer payroll deductions work

Related Topics: Budgeting and Saving (how retirement contributions fit into a savings plan), Taxes (how pre-tax and Roth contributions affect taxable income), Investing (asset allocation and fund selection within 401(k)/IRA accounts)

Next Topics: HSA (Health Savings Account) and its triple tax advantage, Roth conversion strategy for low-income years, Investing fundamentals for choosing what to hold inside retirement accounts