When a family reaches the point of building a structure around its wealth, the first decision is rarely framed correctly. It arrives as a question about cost or staffing. What the family is actually choosing is who holds the relationship with its own affairs, and how much of that relationship it is willing to share.
The choice between a single family office and a multi-family office sits underneath almost every later decision about governance, investment and succession. It deserves to be made deliberately, not inherited from whoever advised the family first.
The two models in short
| Single family office | Multi-family office | |
|---|---|---|
| Who it serves | One family, exclusively | Several client families at once |
| Ownership and control | Built, staffed and controlled by the family | A service the family buys; controlled by the provider |
| How it is paid | By the family it serves | Client fees, and often product or fund-provider income too |
| Where loyalty sits | Undivided; the family's interest comes first | Divided across clients, and shaped by how the office earns |
| What it costs | Full fixed cost borne alone: around 20 bps of assets at scale, above 60 for smaller offices | Typically 0.5%–1% of assets a year (50–100 bps) for full service, often plus fixed retainers; smaller portfolios pay the higher end |
| Best suited to | Larger or more complex families wanting control and continuity | Smaller or less complex families wanting a reliable bought-in service |
Cost ranges: single family office operating costs, Campden Wealth 2025; multi-family office fees, industry surveys (Greenlock, Aleta). The two are not measured identically: the single-office figure is the all-in cost the family bears, the multi-office figure is the fee it is charged. Both represent what the model costs the family. The detail behind each row follows below.
What each model actually is
A single family office serves one family. It is built, staffed and controlled by that family alone. Its people and its priorities answer to no one else. A multi-family office serves several families at once, pooling expertise and infrastructure across them and charging each for access to it.
The difference runs deeper than headcount. A single family office is the family's own house. A multi-family office is a service the family buys. Both can be run well, and both employ capable people. They answer different questions about ownership and control, and that is where the comparison should begin. Our guide to how to set up a family office sets out the wider set of choices these two models sit within.
The real question is control, not cost
Most comparisons start with the price tag. That is the wrong end of the problem. The question that matters is how much of the stewardship of the family's wealth stays inside the family.
What we have always seen in single family offices is that the value sits in proximity. The people running the office know the family, its history and its quiet tensions. They are present at the table when decisions are made, and they carry the family's interest above any other. A multi-family office can be excellent at execution. It is, by design, serving more than one principal. When two client families want the same scarce attention in the same week, the office has to choose between them.
This is the line we draw. Technical execution can be delegated without loss. Custody, reporting, tax administration and trading run perfectly well outside the family. Stewardship is a separate matter. The strategy, the governance and the voice that represents the family belong with the family. A multi-family office that quietly absorbs those decisions has changed what the family controls, often without the family noticing.
Where the economics of sharing make sense
Cost is a real consideration, and the figures reward honesty. The economies of scale in running a dedicated office are steep: larger single family offices operate at roughly 20 basis points of assets, while smaller ones can carry costs above 60 (Campden Wealth 2025). A family with a few hundred million in assets therefore pays a high effective rate to run an office of its own.
That spread is the case for a multi-family office in plain terms. Sharing the infrastructure of a multi-family office spreads the fixed cost of systems, compliance and senior people across several balance sheets. For a family at the lighter end of the wealth range, the arithmetic can favour the shared model, and there is no shame in choosing it.
The arithmetic changes with size and complexity. As assets grow, as direct holdings and operating businesses enter the picture, and as the family spreads across jurisdictions and generations, the dedicated office stops looking expensive and starts looking proportionate. The cost per basis point falls, and the value of undivided attention rises. Families weighing this should read our breakdown of the cost structure of a single family office before assuming either model is the cheaper one.
A point worth checking: how a multi-family office earns
The multi-family office began as a useful idea. Families pooled the cost of the functions no one wants to build alone: administration, accounting, reporting, and access to specialists in law and tax. Shared across several families, these services were cheaper and often better than what one family could assemble on its own.
Most multi-family offices have since moved beyond that role. The majority now operate as wealth managers. Their core business is managing money and distributing financial products, with the administrative service wrapped around it. That shift matters, because it changes how the office earns its living, and from whom.
A family should be able to answer one question before it signs: how does this office actually make its money? A flat fee paid by the family, invoiced and transparent, keeps the relationship clean. Income that arrives from elsewhere does not. Retrocessions from fund managers, placement fees on products, commissions from banks, and revenue-sharing on in-house funds all pull the office's attention towards what pays it rather than what serves the family. The office can be competent and conflicted at the same time, because the incentive is built into the model, not into the people.
The test is straightforward. Ask for every source of the office's revenue in writing, including what it receives from third parties on the family's assets. An office that serves the family will answer plainly. The economics should be visible, and they should point in one direction: towards the family that pays.
What you keep and what you delegate
The two models are not a clean binary, and treating them as one leads families either to over-build or to hand over too much. The useful framing is a question of layers. Which functions sit inside the family's own house, and which are bought in from outside?
Many families settle on a hybrid. They keep a small, trusted core that holds strategy and governance, and they buy specialist execution from outside providers. Strategic asset allocation tends to stay in-house in the large majority of family offices (UBS Global Family Office Report 2025), while legal work, trading and cybersecurity are routinely delegated. A family weighing the single versus multi-family question is really deciding where to draw that internal line. Our guide to what to keep in-house and what to delegate sets out how families make that call in practice.
The discipline is to delegate the work without delegating the judgement. A multi-family office can carry a large share of the operating load. The moment it begins setting the family's priorities rather than serving them, the family has given away something it should have kept.
How families actually decide
In practice the decision turns on a handful of honest signals rather than a formula.
Scale and cost come first. Below a certain size, a dedicated office is hard to justify on economics alone, and a multi-family office or a lean hybrid does the job well. Complexity comes next. A portfolio of liquid assets is straightforward to administer at arm's length. Operating companies, direct real assets and concentrated holdings need people who live close to them.
Then there is the family's appetite for control. Some families want to be deeply involved in how their wealth is run, and they want the office to be unmistakably theirs. Others would rather buy a reliable service and spend their attention elsewhere. Both are legitimate positions. Naming the preference openly prevents the slow drift into a structure nobody actually chose.
Time horizon matters as well. A family preparing to pass wealth and responsibility to a next generation has reasons to build its own office, because the office becomes the place where the next generation learns the work. Provider quality is the final filter, and a sobering one. Whichever model a family chooses, the provider relationship has to be tested before it is trusted.
The model is a tool, the family is the point
A single family office and a multi-family office are both instruments. Neither one guarantees good stewardship, and neither prevents a poor decision. The deeper a family understands what it is choosing, and what it is handing over, the better the structure will serve it.
The right answer is the one the family can explain to itself: what it keeps, what it delegates, and why. That clarity is worth more than any saving measured in basis points.
How Westwick helps
We have seen many family office cost bases drift well past what is reasonable, and past what the comparable market would charge, in both single and multi-family offices. It happens quietly, as fees go unchallenged and a structure outgrows the job it was built for.
We support families on both sides of this decision. For a family choosing a model, we begin from what it actually needs at each time horizon, set out the options and the challenge each one carries, and then carry the chosen decision through to implementation.
For a family that already has an office, we audit what is in place: its costs against the market, how well it runs day to day, and where it has drifted from what the family needs now. In one such review, we brought the cost base down by close to 50 basis points without removing a single service the family relied on, by renegotiating contracts that had gone unchallenged for years. The family comes away knowing where it stands, and what is worth changing.
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