Business Sale Retirement Calculator: Will Your Proceeds Last?

You've sold — or are planning to sell — a business worth $5M, $12M, or $30M. The after-tax proceeds look substantial. But substantial is relative: a $7M portfolio supporting $200,000 in annual spending at age 62, with no Social Security for five more years, must last 30+ years. Whether that works depends on your return assumptions, inflation, and Social Security timing — and the math isn't intuitive. This calculator models your specific numbers year by year.

The 4% rule and why it matters for business sellers

The 4% rule comes from financial planner William Bengen's 1994 research and the subsequent "Trinity Study"³: a retiree withdrawing 4% of their initial portfolio balance (adjusted annually for inflation) has historically sustained that withdrawal for at least 30 years across most historical market scenarios. The implication: you need at least 25× your annual spending to retire sustainably — a useful first-order check.

For business sellers, the rule runs into complications in two directions. First, many close a sale at 55–62, facing a 35–40 year retirement — longer than the original 30-year study period. At 40 years, researchers estimate a sustainable withdrawal rate drops to 3.3–3.5%, implying a 28–30× spending portfolio requirement. Second, the rule assumes full immediate investment of the starting balance; business sellers often have large immediate tax bills, deal-close costs, and illiquid hold-backs that delay how much actually gets invested at close.

Sequence-of-returns risk — the most underappreciated retirement threat

A 6% average annual return over 30 years does not mean a safe 6% annual return. The order of returns matters enormously when you're drawing from the portfolio. A market crash in years 2–3 of retirement depletes far more capital than the same loss in years 28–30, because you're selling shares at depressed prices from a larger base at the moment you can least afford it — and the portfolio has less time to recover.

Business sellers face a specific version of this risk: businesses sell best near economic peaks (buyers are confident, credit is available, multiples are high). Sellers who close at a market top and reinvest proceeds into a diversified portfolio may enter retirement just as that same cycle corrects. This doesn't mean don't sell — it means the post-sale portfolio construction and spending flexibility matter more than the average-return assumption in isolation.

What this calculator doesn't model

• Income taxes on portfolio withdrawals. If most assets are in pre-tax accounts (traditional IRA, 401(k)), each withdrawal is taxable as ordinary income. A $180,000 gross withdrawal at a combined 30% effective rate nets only $126,000. To model this, either inflate your spending target by your effective tax rate, or use a lower expected return to reflect the tax drag on your reinvestable balance.
• Required minimum distributions (RMDs). Under SECURE 2.0, RMDs begin at age 73 for those born 1951–1959 and at age 75 for those born in 1960 or later.⁴ RMDs force taxable withdrawals that may exceed your planned spending, accelerating tax bills and compressing the Roth conversion window you may have in the first few post-sale years.
• Healthcare costs before Medicare. If you're retiring before 65, individual health coverage is a significant line item — plan accordingly. After 65, Medicare Part B plus a supplemental plan adds real annual cost per person. These are ongoing recurring expenses that belong in your spending figure.
• Large lumpy expenses. Home renovation, second home, long-term care costs, education gifts, estate equalization payments. The linear spending model doesn't capture one-time outlays that can meaningfully shorten your runway.
• Retained or rollover equity. If you kept PE rollover equity or an earnout, that asset isn't modeled. A successful second-bite event materially changes the picture — in both directions (additional liquidity, or an unexpected impairment).
• Social Security spousal and survivor benefits. This calculator models a single benefit stream. A married couple's optimization — whose benefit to delay, which spouse claims early, survivor benefit planning — is more complex and materially changes the optimal claiming strategy.