How Much Do I Need to Retire? A Tax-Accurate Answer

A single filer who spends $60,000 per year needs to withdraw $66,172 from a Traditional 401(k) to net that amount after 2025 federal income taxes — and $70,700 if you add a 5% state tax. The popular "25× expenses" rule applied to the after-tax number gives $1,500,000. Applied to the actual gross withdrawal, you need $1,654,000 to $1,843,000 depending on your state. That 10–23% gap is real money most retirement articles ignore entirely.

The 25× rule (also written as "the 4% rule in reverse") comes from the Trinity Study by Cooley, Hubbard, and Walz (1998) and William Bengen's 1994 research. Both studied portfolio survival rates — neither modeled income taxes on withdrawals. The rule tells you how much your portfolio can safely distribute. It does not tell you how much of that distribution you keep.

The 25× Rule Misses Taxes — Here's What That Costs You

The 25× shorthand treats every dollar withdrawn as a dollar spent. But Traditional 401(k) and IRA withdrawals are ordinary income, taxed at your marginal federal rate plus state taxes. The gap between gross withdrawal and net spending depends on three variables: your filing status, your total taxable income, and your state of residence.

For a single filer with no other income withdrawing from a Traditional 401(k) in 2025:

• The first $15,000 is shielded by the standard deduction (Rev. Proc. 2024-40)
• The next $11,925 is taxed at 10%
• The next $36,550 is taxed at 12%
• Dollars $63,475 through $118,350 are taxed at 22%

A $60,000 spending need does not require $60,000 in withdrawals. It requires enough to cover spending plus the tax on the withdrawal itself. This circular dependency — taxes on the money used to pay taxes — is what most calculators skip.

The Real Math: Gross vs. Net Withdrawal

The relationship between spending and required withdrawal is straightforward once you include brackets. You solve for the gross amount W where W minus taxes on W equals your target spending.

Worked Example: Single Filer, $60,000 After-Tax Spending (2025 Brackets)

Given: Single filer, $60,000/year spending, 100% Traditional 401(k), no other income.

Step 1: Identify applicable brackets. With a $15,000 standard deduction, taxable income = W − $15,000. For W near $66,000, taxable income is ~$51,000, which lands in the 22% bracket ($48,475–$103,350).

Step 2: Solve for W. Total federal tax on taxable income of $51,172:

• 10% on first $11,925 = $1,192.50
• 12% on next $36,550 = $4,386.00
• 22% on remaining $2,697 = $593.34
• Total federal tax: $6,171.84

Step 3: Verify. $66,172 − $6,172 = $60,000 after-tax spending. ✓

Step 4: Convert to portfolio requirement. At a 4% withdrawal rate: $66,172 ÷ 0.04 = $1,654,300

The naive calculation ($60,000 ÷ 0.04 = $1,500,000) is short by $154,300.

With state taxes added:

State Tax Rate	Gross Withdrawal	Federal Tax	State Tax	Net Spending	Portfolio at 4%
0% (TX, FL, NV)	$66,172	$6,172	$0	$60,000	$1,654,300
5% (CO, NC, UT)	$70,704	$7,169	$3,535	$60,000	$1,767,600
8% (CA, NY, NJ)	$73,734	$7,835	$5,899	$60,000	$1,843,350

The difference between retiring in Texas versus California on this scenario: $189,050 in additional required savings.

How Account Type Changes Your Number

Not all retirement dollars are taxed equally. The account type determines whether you owe taxes on withdrawal, on gains, or not at all.

Account Type	Tax on Withdrawal	Required Portfolio for $60K Net Spending	Effective "Bonus" vs. Traditional
Traditional 401(k)/IRA	Ordinary income rates	$1,654,300 – $1,843,350	Baseline
Roth 401(k)/IRA	None (qualified)	$1,500,000	Save $154K–$343K
Taxable brokerage (LTCG)	0–15% on gains only	~$1,550,000–$1,620,000	Depends on cost basis
50/50 Traditional/Roth	Blended	~$1,577,000–$1,672,000	Middle ground

The Roth advantage compounds over a multi-decade retirement. A 30-year retirement at $60,000/year spending costs $154,300–$343,000 more in total portfolio if held in Traditional accounts versus Roth — and that assumes tax rates stay constant. If rates rise, the Traditional penalty widens.

This is why Roth conversion ladders are a core FIRE strategy: converting Traditional balances to Roth during low-income early retirement years shifts future withdrawals from taxable to tax-free.

How Much Do You Need at Each Retirement Age?

Retirement age changes the equation in three ways: (1) years of self-funded health insurance, (2) Social Security availability, and (3) portfolio survival period.

Portfolio requirements by retirement age (single filer, $60K after-tax spending, Traditional 401(k))

Retirement Age	Health Insurance Cost	Social Security	Adjusted Annual Need	Portfolio Required (4% rule)
40	$8,000/yr for 25 years	$0 until 62+	$68,000 spending → $79,000 gross	$1,975,000
50	$10,000/yr for 15 years	$0 until 62+	$70,000 spending → $81,500 gross	$2,037,500
55	$12,000/yr for 10 years	$0 until 62+	$72,000 spending → $84,000 gross	$2,100,000
60	$14,000/yr for 5 years	$0 until 62	$74,000 spending → $86,500 gross	$2,162,500
65	~$2,100/yr (Medicare Part B)	$24,000/yr (age 67 FRA, reduced at 65)	$38,100 spending → $42,700 gross	$1,067,500

Two inflection points stand out. The jump from age 60 to 65 cuts the required portfolio nearly in half — Medicare and Social Security together eliminate $30,000–40,000/year in costs. Retiring at 40 versus 55 adds only $125,000 to the portfolio target, because health insurance premiums rise steeply with age.

These numbers assume the 4% withdrawal rate over all time horizons. A 40-year-old retiree faces a 50+ year retirement where 3.25–3.5% may be more appropriate per updated research from the ERN Safe Withdrawal Rate Series. At 3.5%, the age-40 portfolio requirement rises to $2,257,000.

For a detailed analysis of when Social Security timing affects your break-even, see our Social Security claiming strategy guide.

Your Actual Retirement Number: A Three-Step Formula

Forget the single-number heuristics. Your tax-adjusted retirement number requires three inputs:

Step 1: Calculate your gross withdrawal requirement.

Gross withdrawal = After-tax spending ÷ (1 − effective tax rate)

Your effective tax rate depends on filing status, withdrawal amount, and state. For a single filer withdrawing $66,000 from a Traditional 401(k) in 2025, the effective federal rate is 9.3%. Add your state's marginal rate for the complete picture.

Step 2: Add non-portfolio costs before Social Security.

If retiring before 65, add annual health insurance premiums. If retiring before 62 (or whenever you plan to claim), add years × cost to your total portfolio need — or fund these from taxable accounts where withdrawal sequencing minimizes the tax hit.

Step 3: Apply a safe withdrawal rate appropriate to your time horizon.

Retirement Duration	Suggested SWR	Source
30 years (retire at 65)	4.0%	Bengen (1994), Trinity Study (1998)
40 years (retire at 55)	3.5%	ERN SWR Series
50+ years (retire at 40)	3.25%	ERN SWR Series, variable percentage

Your portfolio target = Gross annual withdrawal ÷ SWR.

CoastIQ's Retirement Date Finder runs this calculation across thousands of market scenarios using your actual account balances, tax filing status, and state — producing a probability distribution rather than a single point estimate.

The Compound Cost of Ignoring Taxes

A $154,000 portfolio gap doesn't just mean $154,000 more in savings. It means years of additional accumulation.

At a $25,000/year savings rate with 7% nominal returns, closing a $154,000 gap requires 4.7 additional working years. A $343,000 gap (high-tax state) requires 9.1 years. These are years of your life traded for a calculation error that takes 10 minutes to fix.

The retirement calculator accuracy problem isn't theoretical — it directly determines when you can stop working.

Frequently Asked Questions

How much money do I need to retire at 55?

To retire at 55 spending $60,000/year after tax from a 100% pre-tax portfolio, you need approximately $1.65–2.0M depending on state taxes. Your gross withdrawal must be $66,172 (no state tax) to $73,734 (8% state tax) to net $60,000 after brackets. At a 3.5% safe withdrawal rate (appropriate for a 40+ year retirement), the range is $1,890,000–$2,107,000. Add $12,000/year for health insurance until Medicare at 65, increasing the portfolio need by $343,000 at 3.5% SWR.

How much do I need to retire at 65?

At 65, two expenses disappear: private health insurance (replaced by Medicare Part B at ~$2,100/year) and the full spending burden (offset by Social Security). A single filer expecting $24,000/year from Social Security and spending $60,000/year needs the portfolio to cover $38,100/year ($60K − $24K + $2,100 Medicare). After tax adjustment on the Traditional portion, the gross need is ~$42,700. At 4% SWR: approximately $1,067,000. That's half the age-55 requirement.

Is $1 million enough to retire?

$1 million in a Traditional 401(k) generates $40,000/year at the 4% rule. A single filer pays $2,762 in federal tax on that withdrawal (2025 brackets: $15,000 standard deduction, then 10% on $11,925 and 12% on $13,075 of taxable income). After-tax spending: $37,238. With 5% state tax: $35,238. If your annual spending fits within $35,000–$40,000, $1 million is enough. If your spending exceeds that, it is not — regardless of what the 4% rule implies before taxes.

How much should I save for retirement by age 40?

Fidelity's guideline is 3× your salary by 40, targeting retirement at 67 with Social Security. For early retirement at 50, you need roughly 60% of your target saved by 40 — compounding at 5% real returns covers the rest. Targeting $1,654,000 (the tax-adjusted number for $60K spending) at age 50 requires approximately $1,016,000 at age 40. That's significantly above Fidelity's 3× guideline because FIRE eliminates the Social Security bridge that Fidelity's model assumes.

How much money do you need to retire comfortably?

"Comfortably" for a $150,000 household typically means $105,000–$120,000/year. For a single filer spending $105,000/year from a Traditional 401(k): gross withdrawal needed is ~$126,000 (effective federal rate of ~16.7% at that income level). At 4% SWR, that's a $3,150,000 portfolio. A 50/50 Traditional/Roth split reduces this to $2,850,000 because half the withdrawals are tax-free. State taxes can add another $200,000–500,000 to these figures.

When should you start planning for retirement?

Compound interest makes early starts disproportionately valuable. $500/month at 7% nominal returns from age 25 to 60 accumulates $1,066,000. The same $500/month from age 35 to 60 accumulates $507,000 — less than half the outcome for only 10 fewer years. Starting at 25 versus 35 with FIRE targeting $1,654,000 means saving $500/month versus $1,090/month. The later you start, the more your savings rate must compensate for lost compounding. A Coast FIRE calculation tells you exactly when your existing savings can compound to your target without additional contributions.