A multi-family office is a wealth management firm that delivers family-office services — investment management, tax, estate administration, consolidated reporting, and household administration — to multiple unrelated families, and which unlike a single-family office must register as an investment adviser.
In plain terms
A private office only pencils out above a certain size, because the payroll is fixed and the assets are not. A multi-family office solves that by spreading one set of professionals across many families. Each gets a version of what a single-family office provides — a dedicated team, consolidated reporting across every account and entity, tax and trust work in-house — and pays a fee rather than a payroll. What it gives up is exclusivity, and the ability to ask the office to do genuinely unusual things.
How it works
The legal difference is the whole difference. The SEC’s family office rule excludes an office from the Investment Advisers Act only if it has no clients other than family clients of one family, is wholly owned by them, and is controlled by them. A firm serving several unrelated families fails all three tests at once. It therefore registers — with the SEC once regulatory assets under management reach $110 million, with a state securities regulator below that, under the Form ADV instructions.
Registration is not paperwork. It brings a fiduciary duty enforceable by the Commission, SEC examination, a code of ethics, custody-rule requirements, and — the part that matters most to a prospective client — a public Form ADV Part 2A brochure disclosing the firm’s fees, conflicts of interest, and disciplinary history. Anyone can read a multi-family office’s brochure before hiring it. Nobody outside a family can read anything about that family’s own office.
The label itself, though, is unregulated. “Multi-family office” appears in no statute. Any registered adviser may use it, which is why the term spans firms with $37 billion and firms with $300 million.
The numbers
- Registration threshold: $110 million in regulatory assets under management requires SEC registration; $100 million permits it; below $100 million, state registration generally applies.
- A worked example, from a filing: Silvercrest Asset Management, a publicly traded multi-family office, reported $37.0 billion in assets under management as of December 31, 2025, across 828 client relationships averaging $44 million each. Its top 50 relationships averaged $475 million (FY2025 Form 10-K).
- Staffing at that firm: 171 full-time and three part-time employees against 828 relationships, of which nine professionals are dedicated to family office services specifically — financial planning, tax preparation, partnership accounting, consolidated reporting, trust agency, and art management (FY2025 Form 10-K).
- Client retention there: an average of 98% annually since 2006.
- Typical published minimums across the sector, 2026: commonly $10 million to $25 million of investable assets, though these are firm policies rather than regulatory requirements and vary widely.
- Jurisdiction: United States.
What people get wrong
That the choice between a single- and a multi-family office is a question of price and privacy, with the private version being better if you can afford it. On the two things a client should care about most — enforceable duty and disclosed conflicts — it runs the other way. A multi-family office is supervised by the SEC, owes a fiduciary duty the Commission can act on, and must publish what it charges and where its incentives are misaligned. A single-family office is supervised by the family that owns it, which in practice often means by whoever the family trusts most, using information only that person fully understands.
The fee comparison is also rarely apples to apples. A multi-family office’s stated rate is one number covering advisory, reporting, and administration. A single-family office’s true cost is salaries, benefits, premises, technology, audit, and legal — none of which appears as a fee, all of which appears as an expense, and much of which is not deductible.
Related
Read more: Family Office: How the Very Rich Organize Their Lives and Money · Money Management: From Wealth Manager to Family Office · Wealth Levels: Life at $1M, $10M, $100M, and $1B
See also: Single-family office · Accredited investor · Endowment model · Estate manager