Retirement Accounts: 401(k), IRA, Roth, HSA

Tax-advantaged accounts are the single biggest legal gift the tax code offers investors. This guide explains every major account type, the traditional vs Roth decision with real numbers, and the order in which to fill them.

By Karanvir Singh, founder of Quantix Invest

Why tax-advantaged accounts matter

In a regular taxable brokerage account, the government taxes you three ways: on the income you earned before you invested it, on the dividends and interest along the way, and on the capital gains when you sell. Retirement accounts remove at least one of those layers, and sometimes two.

The effect compounds. Suppose you invest $10,000 a year for 30 years at a 7 percent return. In a tax-advantaged account you end with roughly $945,000. In a taxable account where dividends and rebalancing cost you about 0.5 percent a year in tax drag, you end with roughly $860,000. That is an $85,000 difference from tax treatment alone, before considering that the taxable money was also smaller going in because you paid income tax first.

One note on numbers throughout this guide: contribution limits change with inflation almost every year. Recent figures are given so you have a realistic sense of scale, but always check current IRS limits before contributing. As a reference point, the employee 401(k) limit has been in the low $20,000s recently (around $23,500 in 2025), the IRA limit around $7,000, and the HSA limit around $4,300 for individuals and $8,550 for families, each with catch-up amounts for older savers.

Traditional vs Roth: the real math

Almost every account type comes in two flavors:

• Traditional (pre-tax): you deduct the contribution now, the money grows untaxed, and you pay ordinary income tax on everything you withdraw in retirement.
• Roth (post-tax): you pay tax on the money now, contribute what is left, and never pay tax again. Growth and qualified withdrawals are tax free.

The most common mistake is thinking Roth always wins because "tax-free growth sounds better." The math says otherwise. If your tax rate is identical at contribution and withdrawal, the two are mathematically equivalent. This surprises people, so here is the proof with numbers.

Worked example

You have $10,000 of gross salary to invest. Your tax rate is 24 percent now and, let us assume for the moment, 24 percent in retirement. The account grows 8x over your career.

Identical. The commutative property of multiplication is doing the work: 0.76 x 8 equals 8 x 0.76. So the decision comes down to one question: will your marginal tax rate at withdrawal be higher or lower than your marginal rate today?

• If your rate will be lower in retirement, traditional wins. This describes most people, because most retirees have less taxable income than peak-career workers, and because withdrawals fill up the low brackets first (standard deduction, 10 percent, 12 percent) while contributions come off the top bracket.
• If your rate will be higher in retirement, Roth wins. This describes early-career workers in low brackets, residents and students, people expecting large pensions, and anyone who believes tax rates broadly will rise.

The Roth vs traditional debate is not about which account is better. It is about arbitraging your own tax rate across time. Deduct when your rate is high, pay when your rate is low.

Two practical wrinkles favor Roth beyond the pure math. First, Roth dollars are denser: a maxed-out Roth account shelters more after-tax wealth than a maxed-out traditional account of the same nominal limit. Second, Roth accounts have no lifetime RMDs for the original owner, which helps with late-life tax planning and estates. Many investors sensibly hold both types, which also gives flexibility to manage brackets in retirement.

401(k), 403(b), and 457 plans

These are workplace plans. Your employer picks the provider and the fund menu, and you contribute by payroll deduction.

• 401(k): the standard private-sector plan. Employee contributions up to the annual limit (low $20,000s recently, check current IRS limits), plus a catch-up for those 50 and older. Most plans now offer both traditional and Roth contribution options.
• 403(b): the equivalent for schools, universities, hospitals, and nonprofits. Same employee limit as the 401(k). Historically these plans were stuffed with expensive annuity products, so read the fund menu carefully.
• 457(b): offered by state and local governments and some nonprofits. Two remarkable features: it has its own separate limit, so a government worker with both a 403(b) and a 457 can defer roughly double the normal amount, and governmental 457(b) money can be withdrawn without the 10 percent early-withdrawal penalty once you separate from the employer at any age. That makes it arguably the best early-retirement account in existence.

Beyond the employee limit sits a much larger overall limit on total contributions to a 401(k) (employee plus employer plus after-tax, around $70,000 recently). That gap between the two limits is what makes the mega backdoor Roth possible, covered below.

The employer match

Many employers match some portion of your contributions, for example "100 percent of the first 3 percent of salary, then 50 percent of the next 2 percent." A match is an instant, guaranteed return on your money. A dollar-for-dollar match is a 100 percent return on the day of contribution. No investment on earth reliably competes with that.

Worked example

Salary $80,000. Match: 50 percent of contributions up to 6 percent of salary. If you contribute 6 percent ($4,800), the employer adds $2,400. Skip the contribution and you simply forfeit $2,400 of compensation. Over 30 years, capturing that match and investing it at 7 percent grows to roughly $227,000. That is the price of "I'll start contributing later."

One trap: some plans match per paycheck rather than annually. If you front-load and hit the annual limit in June, you may receive no match for the second half of the year unless the plan has a "true-up" provision. Ask HR whether your plan trues up before front-loading.

Vesting schedules

Your own contributions are always 100 percent yours. Employer contributions may vest over time. Common schedules:

If you leave before vesting, the unvested employer money is forfeited. When weighing a job change, unvested balances are a real cost of leaving; a few months of patience near a cliff date can be worth thousands. Vesting applies only to employer dollars, never to your own deferrals or their growth.

IRAs and the backdoor Roth

An Individual Retirement Arrangement is an account you open yourself at any brokerage, independent of any employer. The contribution limit is much smaller than a 401(k) (around $7,000 recently plus a catch-up at 50, check current IRS limits), but you control the provider and can buy nearly anything, which usually means cheaper funds than a mediocre workplace menu.

• Traditional IRA: deductible if your income is below certain thresholds when you are covered by a workplace plan. Above those thresholds you can still contribute, but without a deduction.
• Roth IRA: direct contributions are only allowed below an income phase-out range (starting around $150,000 single and $236,000 married filing jointly recently, check current IRS limits).

The backdoor Roth

High earners locked out of direct Roth contributions use a two-step workaround that is legal and explicitly acknowledged by Congress:

1. Contribute to a traditional IRA as a nondeductible contribution. There is no income limit on this.
2. Convert that traditional IRA to a Roth IRA, ideally soon after. Because the contribution was already after-tax money, the conversion generates little or no additional tax.

The mega backdoor Roth

Some 401(k) plans allow a third contribution type beyond traditional and Roth deferrals: after-tax contributions. These fill the space between the employee limit and the much larger overall limit. If the plan also allows either in-plan Roth conversions or in-service distributions to a Roth IRA, you can convert those after-tax dollars to Roth almost immediately.

Worked example

Overall 401(k) limit roughly $70,000. You defer $23,500 as the employee. Your employer contributes $10,000. That leaves about $36,500 of room for after-tax contributions, all of which can become Roth money. That is roughly five extra Roth IRAs of space per year for people whose plans support it.

Requirements: the plan must permit after-tax (non-Roth) contributions, and it must permit converting or distributing them while you still work there. Convert quickly, because any earnings between contribution and conversion are taxable at conversion. Not all plans offer this; ask your plan administrator specifically about "after-tax contributions" and "in-plan Roth conversion."

The HSA triple advantage

The Health Savings Account is the only account in the tax code with a triple tax advantage:

1. Contributions are deductible (and avoid payroll tax too if made through payroll).
2. Growth is tax free.
3. Withdrawals for qualified medical expenses are tax free, at any age.

Eligibility requires being covered by a qualifying high-deductible health plan (HDHP). Recent limits are around $4,300 individual and $8,550 family, plus a $1,000 catch-up at 55, check current IRS limits.

Rollovers

When you leave a job, you generally have four options for the old 401(k): leave it, roll it to the new employer's plan, roll it to an IRA, or cash out. Cashing out is almost always the worst choice: taxes plus a 10 percent penalty plus permanent loss of tax-sheltered space.

Always request a direct rollover (trustee to trustee). If a check is made out to you personally, the plan must withhold 20 percent and you have 60 days to redeposit the full amount, including replacing the withheld portion from your own pocket, or the shortfall becomes a taxable distribution. Rolling traditional 401(k) money to a traditional IRA or Roth 401(k) money to a Roth IRA is not a taxable event. Converting traditional money to Roth during a rollover is taxable and should be a deliberate decision, not an accident.

Required minimum distributions

Traditional (pre-tax) accounts come with a bill that eventually arrives. Starting at age 73 (rising to 75 for younger cohorts under current law), the IRS requires you to withdraw a minimum amount each year, calculated from your balance and a life-expectancy table. The first-year RMD is roughly 3.8 to 4 percent of the balance and the percentage rises with age.

Missing an RMD triggers a stiff excise tax (25 percent of the shortfall, reduced to 10 percent if corrected quickly). Roth IRAs have no RMDs for the original owner, and Roth 401(k)s no longer have them under current law either. Large pre-tax balances can force RMDs big enough to push retirees into high brackets and raise Medicare premiums, which is why many retirees do Roth conversions in the low-income years between retirement and RMD age, deliberately filling the lower brackets to shrink future forced withdrawals. Inherited accounts follow separate rules; most non-spouse heirs must empty the account within 10 years.

Getting money out early

The 10 percent penalty on pre-59.5 withdrawals scares people into thinking retirement money is locked away. It is not. The main doors:

• Roth IRA contribution basis: your direct contributions (not earnings) can be withdrawn anytime, tax and penalty free.
• The Roth conversion ladder: convert traditional money to Roth, pay the tax, wait five years, then withdraw the converted amount penalty free. Run a conversion every year and after year five you have a rolling pipeline of accessible money. This is the workhorse of early-retiree planning.
• Rule 72(t) / SEPP: commit to "substantially equal periodic payments" calculated by IRS formula, and withdrawals are penalty free at any age. Rigid: once started, payments must continue for five years or until 59.5, whichever is longer, and mistakes retroactively trigger penalties on everything.
• The rule of 55: leave your employer in or after the year you turn 55, and that employer's 401(k) (only that one) can be tapped penalty free.
• Governmental 457(b): penalty free at any age after separation, as noted above.
• Other exceptions: substantial medical expenses, disability, higher education (IRA only), first home up to $10,000 (IRA only), and a modest annual emergency distribution allowance under recent law.

The fire.html guide covers how early retirees sequence these in practice.

The account priority waterfall

With limited dollars and many account types, order matters. The standard waterfall, adjust for your own tax situation:

1. 401(k) up to the full employer match. Nothing beats an instant 50 to 100 percent return.
2. Pay off high-interest debt (roughly 8 percent and above). A guaranteed return at the debt's rate.
3. Max the HSA if you have HDHP coverage, and invest it rather than spending it.
4. Max the IRA (Roth directly, or backdoor Roth if over the income limit), especially if your 401(k) menu is expensive.
5. Max the rest of the 401(k)/403(b)/457 employee limit. Choose traditional vs Roth using the tax-rate logic above.
6. Mega backdoor Roth if your plan allows after-tax contributions and conversions.
7. 529 plans if education funding is a goal.
8. Taxable brokerage for everything beyond, invested tax-efficiently (next guide).

This page is education, not personalized advice. Account rules interact with income, state taxes, and employer plan documents, so verify the details for your own situation and check current IRS limits each January.