Solo Family Office: Running $5M–$100M Without the Institution

Over the last few years, a new idea has taken hold among founders: you don't need a team of 50 to build a successful business. One person with the right tools can run a profitable company, make good money, and build the work around the life they want. It has a name, solopreneurship, and nobody argues with it much any more.

This page takes the same idea to the other side of a founder's life: the money. A solo family office is a family office run by one person, the capital founder. What follows is what the term means, where it sits next to the family offices you've heard of, and what running one looks like in practice at $5M–$100M.

Solopreneurship made the one-person business normal

The trend started with digital creators. Justin Welsh is probably the best-known example: he built his whole business, content, products and courses, with no full-time employees and one part-time assistant. Plenty of founders have done the same with software, SaaS and service businesses, built from day one to be run by one person.

The less obvious part of the model is knowing when to pause. The idea is to grow the business to a level that pays for the life you want, then hold it there. Work the schedule you want, travel when you want, deal with people you like. A software business doing $1m to $10m a year at 80–90% margins funds an excellent life, without a management team, a board, or 60 employees whose problems become your problems.

Not every founder needs a billion-dollar company. Choosing to stop scaling is a decision, not a failure, and many solopreneurs made it deliberately: they could have grown, but chose not to because the extra headcount would cost them the life they built the business for.

AI took it further: the one-person billion-dollar company

Sam Altman said back in 2023 that his group chat with tech-CEO friends runs "this betting pool for the first year that there is a one-person billion-dollar company. Which would have been unimaginable without AI and now will happen." Fortune wrote it up as the one-person unicorn, and the phrase stuck.

To be clear, "one person" has never meant one person doing everything. It means one decision-maker. That founder runs AI agents working around the clock, brings in contractors for what the agents can't do, and hires senior specialists on a fractional basis when the work needs judgement. Maybe one or two people on payroll, probably none. But one person is the captain: they set the direction and make all the decisions, and because nothing waits for anyone's sign-off, they can move much faster than a traditional company.

Whether the first one arrives in 2 years or 10, the direction is clear: every year, the same work needs fewer people. Founders have watched it happen inside their own companies, which is why most of them take the idea seriously.

Why the traditional family office starts around $100m

Now apply the same idea to money.

Wealthy families have run family offices for generations, and the classic version was built for complicated situations: several branches of a family, many heirs, operating businesses in different industries, property in different countries. Some family offices today run like proper investment institutions, with a CIO, analysts and committee papers. Many more keep a low profile and mostly look after the family's business assets. Either way, the model runs on staff, and staff bring their own problems: hiring, managing, retaining, succession, and the politics of a small team handling one family's private affairs.

It's also expensive. On the UBS Global Family Office Report 2025, staff are 67% of a family office's operating costs. J.P. Morgan's 2026 family office report puts the average running cost at about $0.9m a year for offices under $250m. On $30m, that's roughly 3% of your wealth every year, before a single investment decision. Which is why the standard advice has long been: don't build one below about $100m. I ran the build-versus-outsource numbers in an earlier piece, and they still hold.

For families under that line, the industry's answer is the multi-family office: one firm serving several families and sharing staff costs. I've compared the models in the single-versus-multi guide; the short version is that both boil down to choosing which institution serves you. Many founders at this level are asking a different question: can I run it myself?

The staffed model isn't going anywhere, by the way. Deloitte counted 8,030 single-family offices worldwide in 2024, up from roughly 6,130 in 2019, heading for more than 10,700 by 2030. (Those figures are from 2024; no newer edition exists as I write.) But that growth is happening above $100m. Below it, hiring a team never made sense, and that's the group this page is written for.

If you want the full mechanics, the guide Running a Family Office Under $100M walks through operating models, costs, and who does which job. It's free, behind an email: get the guide. What any particular setup should cost depends on circumstances and needs professional advice.

What a solo family office is

Single family office. Multi-family office. Virtual, fractional. Each name in the industry counts something different.

Newer terms fall below the threshold too. Micro family office is pitched at $1m–$30m, below most readers of this page, and nobody introduces themselves as running a micro office. Lean family office describes how an office is built and staffed. Both are fair attempts at the same gap. Neither says who runs the office.

I work in wealth management, and I hear the question behind all this a lot: do I need a family office at $20m, at $40m? For many founders, the honest answer is that they already have one. They run it themselves; some jobs are done well, some aren't done at all, and nobody has named the setup.

So here's the name. A solo family office is a family office run by one person: the capital founder. Three things hold it up. One accountable owner: you stay in control and run the wealth like a business, and no institution makes the calls on your behalf. Top professionals on call: tax, legal and investment specialists engaged when the work arises and paid well, instead of an army of full-time staff. And systems do the heavy lifting: frameworks, software, and increasingly AI agents covering processes that used to need employees.

Solo answers a different question from the other names: who runs the office. One person, the founder. That works the same at $5m and at $100m, and it doesn't compete with the delivery models. A solo family office can buy virtual services or share a fractional CIO and still be solo, because the accountability stays where it was.

One thing to clear up early: solo doesn't mean alone, and it doesn't mean DIY. It means one person is accountable, with top professionals on call. James Currier of NFX put the case against literal solitude in the same Fortune piece: "If you just do it by yourself, you end up being really lonely. You end up not enjoying what you're doing, and you end up making bad decisions." He's right about the risks of doing everything alone. A working solo family office is different: a tax adviser who knows both your countries, a lawyer you trust, an investment manager for the listed money, a bookkeeper keeping the records straight. What's missing is the payroll and the committee. Dan Sutera, in the same article, predicted some one-person unicorns will earn the title on a technicality, using contractors instead of employees. For a startup, that's a technicality. For a family office, it's the whole point.

Roughly seven million people worldwide hold between $5m and $100m, on the UBS Global Wealth Report 2026 count, the bracket I've written about as the emerging wealthy. Hardly any of them will ever build an institution. Most already run their money themselves, with help. The name is just catching up with what they're doing.

The weak spot: key-person risk

The obvious question about a one-person office: what if something happens to that person? The industry treats this as a top risk. J.P. Morgan's 2026 Global Family Office Report surveyed 333 family offices across 30 countries, with an average net worth of $1.6bn. A third named the lack of a succession plan for key decision-makers as a threat to continuity, a third named overreliance on key individuals, and 86% admitted they have no clear succession plan at all. And a solo family office concentrates everything in one person on purpose.

I won't argue the risk away; it's real. But look at who the key person is in each case. At $1.6bn, the person those offices fear losing is an employee: a CIO or an office head who can resign, join a competitor, and take years of knowledge with them. At $5M–$100M, the key person is the owner, and the owner can't resign from their own money. The remaining risks are incapacity and succession, not staff turnover. That's my reading, based on who sits in each sample; the report doesn't make it clear. Treat it as my view.

The fix is boring, and it works. Write the setup down so someone else could pick it up. Make sure a spouse or a co-trustee knows where everything is and who the professionals are. Name, in advance, who steps in if you can't decide. A few days of work, and it answers most objections.

How a solo family office runs in practice

Underneath, every family office does the same five jobs: a written purpose for the money, one consolidated view of everything owned, a decision rule, a review calendar, and one accountable owner. I've covered them in the five jobs every $5M–$100M setup needs, so I won't repeat them here. A solo family office is those five jobs done without the payroll. What's new is who, or what, does the work.

The AI layer takes the operational load. You set up agents to suit your own operations: consolidating reporting across accounts and countries, tracking capital calls, keeping records in the shape your accountants need, flagging what needs your attention, working while you sleep. That used to be back office; now it's software plus supervision. What AI actually changes about running a family office comes down to which jobs the tools take on and which they don't.

The professionals do the judgement work: world-class specialists in tax, legal, finance and investment, hired for the work in front of them on a fractional basis, and paid well for it. The big offices are moving the same way. Crain Currency reported in January that established family offices are shifting to a core of two to five full-time people with a rotating ring of fractional specialists around them. Founders below $100m get there with no employees at all.

A caveat on the evidence: the staff-cost numbers above are public and verified. There's no good data yet on how much of the work the software really replaces, so that part is my view from experience, not a measured fact, and I hold it more loosely than the rest. And I have to be honest: you can't easily replace all the work with AI agents right now. It's early days. But the tools are developing fast, and I think we get there before long.

What it looks like at $30m

Take $30m after a sale as a worked example. A staffed office would cost about $0.9m a year, 3% of everything you own. The solo version: an accountant and a tax adviser (two countries if your life spans two), a lawyer on call, an investment manager or platform for the listed portfolio, one piece of software holding the consolidated picture, AI agents doing the reading, drafting and chasing, and a one-page policy saying what the money is for. Reviews sit in the calendar, quarterly. Decisions stay with you. The professional bill moves with the work instead of sitting there as salaries, so the running cost lands at a small fraction of the staffed version. What's right for any particular setup depends on circumstances and needs professional advice.

How far you take it is your call. Some founders keep it minimal: the five jobs, two or three trusted specialists, a quarterly review. Others run it like an institution, with an investment policy, deal flow and full reporting, and still no employees anywhere in the structure. My own view: just as we're getting one-person unicorn businesses, we'll see $1bn+ solo family office operations. Not many at first, but what one person can run keeps growing, for wealth just as it did for companies.

If your capital sits in the $5M–$100M range and you make the decisions about it yourself, you're already running a solo family office, whether or not you've used the phrase. The open question is the standard it runs to. Citi's 2024 family office survey found 48% of 338 offices have no written page saying what the money is for and what it must never be risked on. That page is the first of the five jobs; it costs nothing, and it's where running solo on purpose starts.

The model's whole point is control. You stay involved: you read the reports, ask the second question, make the decisions. The main way it fails is quiet: a founder hires someone good, gradually stops reading and stops asking, and 6 months later it's that person's office in everything but name. Agents and specialists are there to support the decision-maker. Keep making the decisions and the office stays yours, however far you take it.

New on the Site

Tuesday's Signal made the same argument the short way: why founders with $5M–$100M are already running one, and what the name changes.

Read it: You're Already Running a Solo Family Office