If you have spent any time thinking about retirement, you have heard the 4% rule. Withdraw 4% of your portfolio the first year, adjust it for inflation each year after, and your money should last about 30 years.
It is a useful back-of-napkin estimate. But the number it gives you is calculated in a vacuum. It assumes your portfolio is your only resource, and that every dollar you withdraw is a dollar you can spend. Neither is true for a real retiree.
In reality, three things make a big difference in what you can actually spend, and the 4% rule ignores all three: your other income, your taxes, and your healthcare costs. Income lifts your real number; taxes and healthcare lower it. For most people, the misses add up in your favor, so the rule understates what you can spend, often by a lot.
What the 4% rule can't see
Your other income. Social Security, a pension, rental income, part-time work. The rule looks only at your portfolio, as if it were your only resource. For most retirees it is not. Once income covers part of your spending, your portfolio can support far more lifestyle than 4% of it implies.
Your taxes. 4% of a $1M portfolio is $40,000, but that is a gross withdrawal, not money you can spend. What lands in your pocket depends on which accounts you draw from. A dollar from a Roth, a traditional IRA, and a brokerage account are taxed three completely different ways. The rule treats them all the same.
Your healthcare. Before 65, ACA premium subsidies can swing by five figures depending on your income that year. After 65, higher income triggers IRMAA surcharges on Medicare. Healthcare is one of the largest and most income-sensitive costs in retirement, and the 4% rule does not see it at all.
Your time horizon. The 4% rule bakes in a 30-year retirement for everyone, then locks the rate. But a 45-year-old may need the money to last 50 years and a 72-year-old only 20. One fixed rate cannot fit every horizon, and the rule never asks how long yours is.
What Confidence Spend answers instead
Confidence Spend is the amount you can spend this year, and sustain for the rest of your life, after taxes, given everything you have. It is built from a full projection: your accounts by tax type, federal and state taxes, healthcare costs (ACA subsidies before 65, IRMAA after), Social Security timing, your other income, inflation, returns, and the balance you want left at the end.
It also sets aside the major one-time expenses you have planned, a home, a wedding, a new car, helping the kids. Those are carved out separately, so your Confidence Spend is the ongoing number you can live on year after year, with the big-ticket items already accounted for.
It is an after-tax lifestyle number, personalized to you, not a flat percentage of your portfolio. For the full breakdown of how the number is built and whether you can really spend it every year, see Can you really spend your Confidence Spend?
The same rule, four very different households
To see how far the 4% number can drift from reality, here is what it produces versus Confidence Spend across four households. These match our demo accounts, so the numbers are reproducible.
One note on a fair comparison: both numbers spend down over a lifetime, and neither aims to leave a bequest. The 4% figure is 4% of the portfolio, before tax. Confidence Spend is after tax and built on a conservative floor, an 8-year cash-and-bond buffer plus roughly a 3% real return after that, so a bad market does not force you to sell at the wrong time. The 4% rule stays safe by spending less than you likely can; Confidence Spend manages the downside directly and lets you spend the rest.
| Household | 4% of portfolio | Confidence Spend | Difference |
|---|---|---|---|
| James & Priya, 47 (NC), ~$1.1M | $44,000 | $51,800 | +$7,800 (+18%) |
| Robert & Susan, 56 (CA), ~$1.9M | $76,000 | $90,700 | +$14,700 (+19%) |
| Diane & Tom, 63 (AZ), ~$2.8M | $112,000 | $137,200 | +$25,200 (+23%) |
| Frank & Carol, 69 (FL), ~$2.3M | $92,000 | $125,600 | +$33,600 (+37%) |
Confidence Spend beat the 4% number in every household, by 18% to 37%. The gap was smallest for the youngest couple, retiring early with the longest horizon and no income flowing yet, and it grew steadily as income came online, reaching 37% once Social Security was in hand. The rule was never too generous. It was low every time, because it cannot see your income, your taxes, your healthcare, or how long your money has to last.
The biggest lever the rule ignores: your income
Take Frank and Carol, the couple at 69. On their portfolio alone, after taxes and healthcare, they can sustainably spend $75,400, which is actually less than the 4% rule's $92,000. Add their Social Security and the number jumps to $125,600. That is the whole tug-of-war in one example: taxes and healthcare pull the number below the rule, and income more than makes up for it. The 4% rule cannot see any of it, because it only ever looks at your portfolio.
So what should you do with the 4% rule?
Keep it as what it is: a fast sanity check. If 4% of your portfolio already covers your spending, you are likely in good shape. But do not let it set your lifestyle, in either direction. It will scare an early retiree into underspending, and lull a 70-something into dying with more than they needed.
The number you actually want is age-aware, income-aware, and after-tax. That is your Confidence Spend, and it is usually higher than the rule of thumb lets you believe.
Educational only, not financial or tax advice. Everyone's situation is different. Model your own numbers, or check with a fiduciary advisor or CPA, before acting.