Wealth Building · 11 min read
Your Freedom Number
Work-optional is a dollar figure, not a birthday
Reviewed by Jonathan Shafer, DO, July 2026. Disclosure: the reviewer is the founder and owner of Attending Financial LLC. This is education, not individualized financial advice.
Work-optional is a number, not an age
Ask a roomful of attendings when they can stop working and most name an age: 62, 65, whatever their parents did. Age is the wrong variable. Work-optional status arrives when your portfolio can cover your spending, and that is a dollar figure, not a birthday. A physician spending $12,000 a month needs roughly $3,600,000 by the standard first approximation; at $9,000 a month the target drops to $2,700,000. Nothing about either number requires you to quit medicine. The more useful version for most physicians is partial: the point where clinical income at 0.5 FTE plus a smaller portfolio covers everything, and every shift after that is chosen rather than required. A high income compresses the timeline, but only if you know what you are aiming at. This module shows where the multiply-by-25 heuristic comes from, what the research behind it actually tested and did not test, and how part-time practice cuts the target by seven figures.
One question · thirty seconds · no account
Wealth Building · board-style
A 54-year-old emergency physician spends $180,000 a year after tax and wants to drop to 0.5 FTE, which would net $100,000 a year after tax. She asks what portfolio she needs before making the change, using the multiply-by-25 heuristic. Which figure answers her question?
Freedom number
The portfolio size at which sustainable withdrawals cover your chosen annual spending, approximated as that spending multiplied by 25 — the inverse of a 4 percent initial withdrawal rate.
The freedom number is the standard first approximation of a work-optional portfolio: your chosen annual spending multiplied by 25. The multiplier is simply the inverse of a 4 percent initial withdrawal rate, and the 4 percent figure has a specific pedigree. William Bengen (Journal of Financial Planning, 1994) backtested retirements beginning in every year from 1926 forward, holding 50 to 75 percent stocks, and found that an initial withdrawal of 4 percent of the portfolio, adjusted for inflation each year thereafter, survived every historical 30-year window he tested. The worst cases were retirements around 1966 to 1969, into a stagnant market followed by severe inflation. The Trinity study (Cooley, Hubbard and Walz, AAII Journal, 1998) extended this with success rates across allocations and 15- to 30-year payout periods using 1926 to 1995 data, finding high success rates for 4 percent inflation-adjusted withdrawals from stock-dominated portfolios. Note what that is: a historical, United States, 30-year, worst-case planning heuristic. It is not a guarantee about your future.
Why it matters: Without a number, work-optional stays an anxious abstraction and the default becomes working to an arbitrary age. With a number, every input is visible and adjustable: spending you choose, savings you control, and clinical income you can dial rather than switch off. The number also protects you in both directions — against retiring on too little and against grinding out five unnecessary years past enough.
The bridge number: half-time medicine is worth $2,000,000
A 51-year-old internist spends $12,000 a month and is deciding between saving for a full stop and planning a long part-time chapter.
Bottom line: Half-time medicine cuts the required portfolio from $3,600,000 to $1,600,000 — a $2,000,000 reduction produced by your schedule, not by the market.
What the 4 percent research actually says
The multiply-by-25 heuristic gets repeated as a law of nature. It is a pair of historical studies with specific boundaries. Flip each card to see what was tested, what was found, and where the fine print bites a physician who may retire early or live long.
Where does 4 percent come from?
Bengen, Journal of Financial Planning, 1994. He backtested retirements starting each year from 1926, at 50 to 75 percent stocks, and found 4 percent inflation-adjusted withdrawals survived every historical 30-year window — the worst cohorts retired around 1966 to 1969.
What did the Trinity study add?
Cooley, Hubbard and Walz, AAII Journal, 1998. Using 1926 to 1995 data, they tabulated success rates — a portfolio finishing the payout period above zero — across stock and bond mixes and 15- to 30-year horizons, confirming high success for stock-dominated portfolios at 4 percent.
What was never promised
Both studies used United States historical returns, 30-year maximum horizons, and no advisory fees or taxes. A physician retiring at 52 may need 40 years. The research is a worst-case planning heuristic, not a forward guarantee — future markets are not obligated to repeat 1926 to 1995.
Why the first decade decides
Sequence-of-returns risk: two retirees can earn identical average returns, but the one who hits a bear market early — while withdrawing — sells depressed assets that never recover. Poor returns in the first retirement decade drive most historical failures, which is why income during those years matters.
The clinical glide path: three exits from full-time
The freedom number tells you when work becomes optional. It does not tell you how to step down. Consider a 52-year-old anesthesiologist with a $2,600,000 portfolio, household spending of $144,000 a year after tax, and a full freedom number of $3,600,000. Full-time work leaves about $120,000 a year to invest. Three plans are on the table.
You are 52, tired but not done. Your portfolio is $2,600,000 against a $3,600,000 target, and you can choose your trajectory for the next ten years.
Hard stop: retire fully the day the portfolio touches $3,600,000, likely by 55 to 57
You reach the number, but the entire $144,000 spending load transfers to the portfolio on day one of a retirement that could run 40 years — beyond the 30-year horizons the research tested. A bear market in your first five years arrives with no income buffer, and you are selling depressed assets to eat. Historically, that early-loss pattern is exactly where 4 percent plans failed.
Glide path: drop to 0.6 FTE at 55, then to zero at 62 — the better choice
At 0.6 FTE your clinical income still covers spending, so the portfolio compounds untouched through the very decade when sequence-of-returns risk is most dangerous. You keep licensure, colleagues, and identity while the target arrives on its own. By 62 the portfolio has grown well past $3,600,000, your remaining horizon is nearer the 30 years the research actually studied, and every year in between was worked by choice.
Full throttle: stay full-time to 62, then stop cold
This produces the largest terminal portfolio and the highest burnout risk — ten more years of call you already resent, buying margin you may not need. The abrupt transition still concentrates the psychological and sequence-of-returns adjustment at a single date. Extra money is a weak trade for a decade of resentment when a glide would have covered the same risk.
Check yourself: the part-time bridge
A colleague is planning her own step-down. Apply the bridge arithmetic to her numbers before you check the answer.
A 56-year-old pediatrician spends $150,000 a year after tax. She plans to work 0.5 FTE indefinitely, netting $70,000 a year after tax. Using the multiply-by-25 heuristic, what portfolio does her part-time plan require?
The heuristic applies to the spending the portfolio must cover, not to total spending or to income. Clinical income of $70,000 handles part of the $150,000, leaving the portfolio a job of $80,000 a year; $80,000 × 25 = $2,000,000. Multiplying full spending by 25 ignores her income and overshoots by $1,750,000, while multiplying income by 25 answers a question nobody asked.
The number is yours to move
- Your freedom number is chosen annual spending multiplied by 25, a first approximation derived from the 4 percent withdrawal-rate research.
- The research behind the heuristic — Bengen 1994 and the Trinity study 1998 — measured historical United States 30-year success, not a forward guarantee, so treat the number as a planning floor with fine print.
- The calculation runs on expenses, never on income; a physician who multiplies income by 25 manufactures a target that is millions too high.
- Part-time clinical income shrinks the portfolio's job dollar for dollar, so a bridge number at 0.5 FTE can sit $2,000,000 below the full target.
- A glide path from full-time through reduced FTE de-risks the first retirement decade, where sequence-of-returns losses cause most historical plan failures.
Do this next: Pull last month's actual spending from your accounts, multiply by 12 and then by 25, and write both your full freedom number and a 0.5 FTE bridge number next to your current portfolio balance.
Keep reading
Compounding on a Physician Timeline
You started 10 years behind. The math of closing that gap — and why compound interest still works in your favor.
Starting at 45: The Late-Starter Protocol
The 15-year recovery plan for physicians who saved little before mid-career
The Drawdown Order
Accumulation had a fill order. Spending has one too — and running it backwards costs six figures.
Net Worth: Understanding Your Number
Most physicians in their thirties have a negative net worth. This is normal. Not knowing it — and not tracking it — is the problem.