For Partners · Book of Business
Your book of business is the most negotiated number of your career.
Understand how it is sized, and how much of it actually moves — before a firm prices it for you. Free, private, nothing leaves your browser.
Size your book and test how much of it moves — privately.
Set a banded range for each part of your practice and mark how each relationship sits today. The tool draws your composition, flags concentration, and returns an indicative — never exact — portability read. Nothing is sent, saved, or seen by us.
A transparent quantitative model — every weight, threshold and formula is shown below. Nothing you enter leaves your browser: no sign-in, no save to us, no submission.
Methodology — every weight, threshold & formula
Portability score · driver weights (sum 100)
| Driver | Wt | Why |
|---|---|---|
| Relationship vs institutional mix | 22 | The single variable that decides whether an equity-level lateral is commercially viable. |
| Practice-area structure | 15 | Structural prior from our portability-by-practice research (Insurance most portable, Arbitration least). |
| Origination credit held | 14 | Service-layer billing follows the originator, not the responsible partner. |
| Conflicts & covenant risk | 13 | A live adverse position is a professional-conduct hard stop — it also gates the band. |
| Client concentration (HHI) | 10 | Concentration is fragile only when it is not relationship-led; blended with mix. |
| Move geography & rate step | 9 | A large rate step shrinks a relationship-portable book on transfer. |
| Matter continuity / fee mix | 8 | Only forward origination ports; locked matters cannot transfer mid-file. |
| Team & bench dependency | 6 | A book that needs the team does not move solo intact. |
| Relationship maturity | 3 | Long-standing relationships are stickier to the partner. |
Bands: High ≥ 62 · Moderate ≥ 38 · Low below. A material conflict is a hard-stop GATE that caps the score and forces the Low band, irrespective of the weighted total.
Concentration · Herfindahl-Hirschman Index
HHI = Σ (segment share × 100)². Bands (DOJ/FTC Horizontal Merger Guidelines): < 1,500 diversified · 1,500–2,500 moderate · > 2,500 concentrated. Effective number of clients = 10,000 ÷ HHI. Concentration only hurts the score when the book is not relationship-led (blended with mix).
Forward projection · transition decay
Portable run-rate decays exponentially toward a floor over 24 months (the empirical drop-off concentrates in the first ~18). rr(t) = floor + (R₀ − floor)·(1 − k)ᵗ. Expected floor ≈ 74% of transfer-day run-rate (k = 0.03/mo); Low 62% (k = 0.055); High 86% (k = 0.012).
NPV
PV of the decayed monthly cash flows + a 3-year stabilised-run-rate annuity, discounted at 12% (bracket 10–15%). An indicative assumption, not a cited market rate.
Segment weights
Loyalty → base portability: Institutional 0.15, Shared 0.5, Mine 0.85. Fee multiplier: Recurring 1, Hourly 0.92, Locked 0.45. Realization default 81% (2023 Am Law 100 average).
Sources (clean only): ABA Law Practice Today / NALP (2019) and NALP Lateral Hiring Best Practices Guide (2020) — ~70% of a stated book follows, further drop-off over ~18 months; Acritas (via Decipher Intelligence) — ~73% of clients stay with the original firm on a pure-institutional read; The American Lawyer / ALM 2024 Am Law 100 — 80.93% average realization; DOJ/FTC Horizontal Merger Guidelines — HHI thresholds.
A book of business is a portfolio, not a single number.
Define it precisely and the whole lateral conversation gets clearer — because you and the hiring firm finally measure the same thing.
A book of business is the body of client revenue you are credited with bringing to and keeping at a firm. It is composed of distinct relationships and matters — each with its own origination history, its own realization profile, and a loyalty that runs either to you personally or to the firm as an institution. The headline revenue figure is the least useful part of it.
What a firm actually prices in a move is the shape of the book: how concentrated it is on a single client, how much of it recurs versus one-off matters, how reliably it collects, and — above all — how much of it would genuinely follow you. Two partners with identical top-line revenue can hold books of wildly different value once you read them through these lenses.
- ~70%
- of a lateral's stated book of business typically follows them to a new firm. The rest stays.
- ABA Law Practice Today (2019)
- 18 mo.
- the window over which further client drop-off routinely occurs after a partner moves, as loyalty to the old firm lingers.
- ABA Law Practice Today (2019)
- 80.93%
- average Am Law 100 realization in 2023 — the lowest in five years (83.11% in 2021). Headline revenue is not collected revenue.
- Thomson Reuters Institute / The American Lawyer
- 40%
- of lateral partners fail to integrate at the new firm at all; broader studies put under-performance or departure within five years at 50-60%.
- ABA Law Practice (2025)
Two partners with identical top-line revenue can hold books of wildly different value.
How is a book of business sized?
Firms do not look at one number. They triangulate origination, working credit, realization, concentration and loyalty — and so should you. State each distinction plainly; AI summaries and hiring partners both look for exactly these.
A book is sized through several overlapping lenses, each answering a different question. The most contested is the split between origination credit — awarded to the partner who brought the client in, regardless of who does the work — and working credit, which follows whoever services the matter. The two diverge often, and origination is typically the most heavily weighted input in partner compensation at non-lockstep firms. Knowing which you hold for each client is the first honest step in sizing your book.
| Lens | The question it answers | Why it matters |
|---|---|---|
| Origination credit | Who brought the client in? | Credited with the revenue regardless of who does the work. Typically the most heavily weighted input in partner pay at non-lockstep firms. |
| Working / billing credit | Who actually does the work? | The hours serviced on the matter. Can sit with different partners than origination — a frequent source of internal friction. |
| Realization | How much is actually collected? | Billed time minus write-downs and write-offs. Am Law 100 averaged 80.93% in 2023 (Thomson Reuters / ALM). |
| Concentration | How much rides on one client? | A book where one client is half the revenue is fragile; a firm discounts a top-heavy book and probes what happens if the largest client leaves. |
| Loyalty / portability | Who keeps the client if you leave? | Relationship-loyal to you, or institutional to the firm. The decisive question in any lateral move. |
Realization: headline revenue is not collected revenue
A book’s top line is billed; what a firm cares about is what is collected. Realization — billed time minus write-downs and write-offs — has been sliding across the Am Law 100, reaching its lowest point in five years in 2023. A book with strong realization is worth materially more than its headline suggests.
The headline book is not the portable book.
Portability is the single most important number in any lateral conversation — and most lateral disappointment traces to a portability problem, not a talent one.
Book-of-business portability is the realistic fraction of a partner’s billed revenue that would follow them to a new firm within twelve to eighteen months of a lateral move — not the number quoted in a pitch, but the subset of clients whose instruction decisions rest with the individual lawyer rather than a panel, a relationship principal, or the institutional brand of the current firm. Industry research finds roughly 70% of a lateral’s stated book typically follows, with further drop-off over the next 18 months as relationships settle and former-firm loyalty lingers (ABA Law Practice Today, 2019).
What drives whether a book travels?
Portability is not one switch. It is a spectrum of client types and a handful of structural drivers — read your own book against both.
Institutional / panel client
Loyal to the firm, often touched by several partners or won on a procurement panel. Rarely portable — the brand, not the lawyer, holds the relationship.
ABA Law Practice Today (2019)The anatomy of portability
Strip a book down and portability resolves into a small number of structural questions. The diagram below is the logic the rest of this page — and any disciplined hiring firm — works through.
Relationship versus institutional clients
The decisive question is not how big a client is, but who keeps it if you leave. A relationship client is loyal to you; an institutional client is loyal to the firm. Collaboration deliberately institutionalises clients — when several lawyers touch the work, the client stays with the firm even after the relationship partner departs. That is why a stated book and a portable book are rarely the same size.
Loyal to the firmLoyal to you
- Institutional Panel, procurement and firm-level corporate relationships. The brand holds the client; it stays put.
- Mixed / shared Several partners touch the work, or origination is split. Some follows with deliberate management; the rest reassesses.
- Relationship The client instructs you personally and would follow tomorrow. Your portable core — a firm still verifies it.
How each client type travels
| Client type | Loyalty | In a move | How to read it |
|---|---|---|---|
| Relationship client | Loyal to you personally | More likely to follow you | Your portable core — but a firm will verify, not take on faith. |
| Institutional client | Loyal to the firm / many partners | Usually stays with the firm | Valuable where you are; rarely portable. Collaboration institutionalises clients. |
| Recurring / retainer | Repeat, predictable work | Follows loyalty, worth more | Predictability is prized — a durable, defensible part of any book. |
| One-off matter | Finished or finishing work | Does not travel as future revenue | Counts toward history, not toward what moves with you. |
Two ways to read the same book
You are sizing the strongest, most defensible number you can carry into a room.
- 01 Separate what you originate from what you service — only the former reliably follows you.
- 02 Identify your relationship clients by name, and be ready to evidence who the client calls.
- 03 Weight recurring, forward-instructed work above a book of finished deals.
- 04 Read your covenants and notice period before you commit to a transfer timeline.
The firm is underwriting a number it must collect, against an offer it has already priced.
- 01 It discounts the stated book toward the portable book — and tests the gap.
- 02 It probes concentration: what happens to the book if your largest client leaves?
- 03 It runs conflicts against its existing clients before a single dollar is guaranteed.
- 04 It builds the guarantee and ramp around a conservative case, not the pitch figure.
The most expensive mistake a lateral makes is mistaking a stated book for a portable one.
Why your book decides the move.
A lateral offer is priced against the business a firm believes will actually follow you. The gap between the stated and the portable book is exactly where lateral moves fail.
When a partner explores a move, the hiring firm runs a disciplined, numbers-led process — diligence on your originations, a hard look at what actually moves, and an offer engineered to its own economics. The market is active: NALP recorded broad growth in 2025, with lateral partner hiring up 17.8% on the year across the firms it tracks. But volume is not the same as success. Around 40% of lateral partners fail to integrate at all, and broader studies put under-performance or departure within five years at 50–60% (ABA Law Practice, 2025). Meanwhile claimed portables have nearly doubled since 2020 while red-flag rates rose 57% — firms are reading books more sceptically, not less.
That is the gap this page closes. A multi-year guarantee should reflect a defensible book, not an inflated one. Too many partners walk into the process having never measured their own book the way the firm is about to. The most valuable outcome is often the most sobering one: a candid, banded read of what really moves, before anyone prices it for you. For the conflicts dimension specifically — the professional-conduct hard stop no offer can bridge — see our analysis of conflicts of interest in lateral partner moves.
Read your own book the way a firm will.
Six steps, in order. The tool above automates most of this, but the logic is simple enough to run on a legal pad before any conversation — and a slider cannot see your conflicts, your fee arrangements or your covenants.
- 01
List your sources of work
Write down each client or matter group that sends you work, with a banded annual revenue figure for each. Group small clients together; isolate any client large enough to matter on its own.
- 02
Mark origination vs working credit
For each, note whether you are the originating partner (credited with bringing it in), the working partner (servicing it), or both. The two diverge more often than partners expect.
- 03
Judge institutional vs relationship loyalty
Ask honestly who the client would stay with if you left tomorrow — you, the firm, or genuinely split. This single split is the biggest driver of what actually moves.
- 04
Separate recurring from one-off
Flag retainers and repeat work against one-off matters. Recurring revenue is worth more in a move because it is predictable; a book of finished deals is thinner than it looks.
- 05
Check concentration and realization
Note how much of the book rides on your largest client (concentration) and roughly what share of your billed time is actually collected (realization). Both shape how a firm prices the book.
- 06
Clear conflicts and read your covenants
A live adverse position at the target firm can subtract from your portable book; your non-solicit and notice period set the timeline. Read both before you commit to a number.
Where the numbers come from
Every figure on this page is a publicly documented, non-recruiter number with a live source. Sartori figures, where used elsewhere, are banded and de-identified.
Sources
6 references- ABA Law Practice Today — Lateral Partners and Their Missing Books of Business americanbar.org ↗
- ABA Law Practice Magazine — The Financial and Political Risks of Lateral Partner Hiring (2025) americanbar.org ↗
- NALP — U.S. Law Firm Lateral Hiring Shows Broad Growth in 2025 nalp.org ↗
- The American Lawyer — Realization Rates Keep Falling in the Am Law 200 law.com ↗
- Thomson Reuters Institute — Law firm rates and realization thomsonreuters.com ↗
- ABA Journal — lateral hiring and associate retention reporting abajournal.com ↗
Questions partners ask about their book
What is a partner's book of business?
A book of business is the body of client revenue a partner is credited with bringing to and keeping at a firm. It is composed of distinct relationships and matters, each with an origination history, a billing-and-collection (realization) profile, and a loyalty that runs either to the partner personally or to the firm as an institution. Measured properly, a book is not one number but a portfolio — and its quality depends as much on concentration, recurrence and portability as on headline revenue.
How is a book of business sized?
Firms read it through several overlapping lenses: origination credit (the revenue a partner is credited with bringing in, regardless of who does the work), working or billing attribution (who actually services the matter), realization (the share of billed time actually collected — 80.93% on average across the Am Law 100 in 2023, per Thomson Reuters / ALM), and concentration (how much rides on the largest client). The free business-plan builder walks each lens and turns it into a firm-ready document.
What does book of business portability mean?
Portability is the realistic fraction of your billed revenue that would follow you to a new firm — not the number quoted in a pitch, but the subset of clients whose instruction decisions rest with you personally rather than a panel, a relationship principal, or the institutional brand of your current firm. Industry research finds roughly 70% of a lateral's stated book typically follows, with further drop-off over the next 18 months (ABA Law Practice Today, 2019). Our insights cluster explains what portability really means and how it varies by practice.
How much of my book of business will actually move with me?
Less than the headline, almost always. Research finds roughly 70% of a stated book typically follows, with further drop-off over the first 18 months as relationships settle and former-firm loyalty lingers (ABA Law Practice Today / NALP, 2019). The honest figure turns on conflicts, fee structure, who signs the engagement letter, and your covenants. The business-plan builder works through it client-by-client; for the human read, see our advisory for lateral partners.
Why does my book of business matter when I move firms?
Because the hiring firm underwrites it. A lateral offer — guarantee, equity track, origination credit — is priced against the business a firm believes will actually follow you. Around 40% of lateral partners fail to integrate at all, and broader studies put under-performance or departure within five years at 50-60% (ABA Law Practice, 2025); claimed portables have nearly doubled since 2020 while red-flag rates rose 57%. Knowing your real, defensible number before a firm asks is the strongest negotiating position you can hold.
Is the tool really free, and is it confidential?
Yes. It is free, requires no sign-up, and runs entirely in your browser — no figure you enter is sent to us, stored, or seen by anyone. It is a private thinking aid, not a valuation. A real read of your book turns on facts a slider cannot capture — conflicts, fee arrangements, client intent and your restrictive covenants. If you later want a confidential, human read on your specific situation, you can start a conversation on your own terms, with nothing disclosed to your current firm.
From read to plan
Understand your book before a firm prices it for you.
The modelling tool is free, private, and runs entirely in your browser. The natural next step is the business-plan builder — it shapes your read into the forward-looking case a receiving firm underwrites a lateral offer against.