Law firm guide
A portable book of business is the client work that would keep coming to you if you changed firms, because the clients choose to follow you. You build one by becoming the lawyer business clients call directly, on work that recurs and grows.
Book a demoLast updated September 28, 2026
The short answer
A portable book of business is the client work that would follow you to another firm because clients choose you: the relationship runs through you and the work recurs. Clients are not property. Build one by picking an industry niche, reaching out to companies at moments that create legal work, and adding adjacent matters. Clean finds those companies and who can introduce you.
A book of business is the client work a lawyer is credited with bringing in and keeping. The portable part is the work that would keep coming to you if you changed firms, because the clients would choose to follow you.
Three tests separate the two. First, the client would follow you: the person who hires outside counsel there knows you and would pick you over the firm's name. Second, the work recurs, instead of ending with one closing that is already billed. Third, the relationship is yours and not only the firm's: you brought the client in or grew it, and you know more than one person there.
The ABA put the premise plainly in Formal Opinion 489 (2019): clients are not property, and subject to conflicts, they decide who represents them when a lawyer changes firms. The same relationships drive your origination credit and your partnership case where you are now. Building a portable book and building a career at your current firm are the same work.
Before any move, you and the new firm need the same answer: which of these clients would actually come. The signals below answer it. Each one is something you can strengthen years before you think about leaving.
Signals that a book of business is portable
| Signal that a book is portable | Why it matters | How to strengthen it |
|---|---|---|
| The person who hires outside counsel calls you directly | After a move the choice is the client's, and clients tend to pick the lawyer they deal with | Build a direct line to the general counsel, CEO or owner, not only the deal team |
| The work recurs | A finished matter does not move. A contract program, lease portfolio or compliance cycle can | Turn one-off matters into standing work: annual reviews, form agreements, a spot on the client's panel |
| You do the core work yourself | If the work depends on colleagues or firm resources you would leave behind, the client may stay | Build depth in the work you personally handle |
| You know several people at the client | One contact leaving can end a relationship at any firm | Know the GC, the CFO and the next person in line |
| Your rates fit the client's budget | A client that cannot pay a new firm's rates may not follow, however loyal | Know each client's budget and who approves invoices |
| No conflicts where you might go | A client the new firm is conflicted out of cannot follow you | Keep an accurate record of clients, matters and adverse parties in the firm's conflicts system; at a move, share only what Rule 1.6(b)(7) allows |
| Your origination history is documented | Firms read credit history as evidence of who brought the work in | Write down how each client and matter came to you, with dates |
Firms hiring a lateral partner commonly ask for origination and collections history for recent years, your billing rates, a client and matter list for conflict checks, and your own estimate of which clients will follow and why. They commonly discount institutional clients you were assigned, work that depends on the old firm's bench or offices, and matters that are already finished.
Be conservative in that estimate. An overstated book shows up in the first year's collections, and your standing with the new partners goes with it.
Conflicts come first. ABA Model Rule 1.6(b)(7) lets a lawyer reveal client information, to the extent the lawyer reasonably believes necessary, to detect and resolve conflicts arising from a change of firms. It applies only if the disclosure would not compromise privilege or otherwise prejudice the client.
Under Rule 1.10, a conflict you bring is generally imputed to every lawyer at the new firm. The screening exception is narrow: it covers former-client conflicts that arise from your old firm, and only if you are timely screened, take no part of the fee, and the former client gets prompt written notice. It does not reach conflicts involving clients you still represent; those need the affected clients' informed consent, where Rule 1.7 allows it. Check your state's version, because a client you cannot represent there is not part of your portable book.
The rules on changing firms put the client first. ABA Formal Opinion 489 (December 4, 2019), building on Formal Opinion 99-414 (1999), sets out the Model Rules position:
Origination credit is a firm's internal record of which lawyer brought in a client or a matter. It feeds compensation and partnership decisions, but it is accounting inside one firm, not a measure of what would follow you. A client credited to you may stay when you leave, and a client credited to a retired partner may follow the lawyer who does the work.
Two things hold under any system. Get your firm's rules in writing, and keep your own dated record of how each client and matter came in, because a firm hiring you laterally will commonly ask for your origination history. How credit shapes partner pay, and the questions to ask your firm about it, are in how to become a rainmaker.
There is no standard system. The common approaches, which firms mix in different ways:
Firms commonly decide partnership on legal skill, judgment, hours and business: the clients and matters you bring in or grow. Many firms have a non-equity or income partner tier below equity partnership, and the business case commonly weighs most at the equity step. Ask your practice group leader for the written and unwritten standards.
Origination is the part you control earliest. Start with new matters inside existing clients: the lease after the acquisition, the subcontract after the contract win. Then add a few clients of your own in one industry. A steady run of new matters from clients you developed is a portable book in its early form. For the habits behind it, see how to become a rainmaker and the weekly routine in business development for lawyers.
A portable book is built one company at a time. For a lawyer whose clients are businesses, five steps do most of the work.
Clean does the research behind the second step. It finds companies at moments that create legal work: a large contract won, a real estate deal or new site, new import activity, a new license or registration, or an acquisition. For each company it gives the reason, the practice area it touches, the person who hires outside counsel, and who in your team's network can introduce you. Every reason comes with the record behind it, so you can check it before you write.
You set the search by industry, company size, region and the kind of matter you want, and leave out current clients. Clean does not send messages for you. You decide whether and how to reach out, and you run conflicts first. Book a demo to see companies in your market with a moment that creates work in your practice, and who to reach, or start at Clean for law firms.
A portable book of business is the client work that would keep coming to a lawyer after a move to another firm, because the clients choose to follow. It rests on three things: the person who hires outside counsel deals with that lawyer directly, the work recurs, and the lawyer built the relationship personally. Clients are never property, so portability is always the client's decision.
Pick an industry and practice niche, then find companies with a moment that creates legal work there, such as a contract win, a new site or an acquisition. Run conflicts and check your state's solicitation rules, then send a truthful letter or email as the first touch, or ask for a warm introduction. Then grow each client through adjacent matters and get to know more than one person there.
Firms commonly ask for origination and collections history for recent years, billing rates, a client and matter list for conflict checks, and the lawyer's own estimate of which clients will follow and why. They tend to discount institutional clients the lawyer was assigned, work tied to the old firm's resources, and finished matters. A conservative estimate that the first year's collections bear out protects the lawyer's standing.
No. Origination credit is one firm's internal record of which lawyer brought in a client or matter, and it stays with that firm's compensation system. What can move is the client, and only if the client chooses to follow. Firms hiring a lateral commonly ask for origination and collections history as evidence of who brought the work in, so keep your own dated record of how each client and matter came to you.
The decision belongs to the client. Under ABA Formal Opinion 489, lawyers may leave, non-compete clauses are not allowed, and clients choose whether to stay, follow the departing lawyer or pick someone else. Under the Model Rules you need not wait to tell clients, as long as the firm is told at the same time. Some states are stricter: absent an agreement otherwise, Florida requires a departing lawyer to try to negotiate a joint notice with the firm first.
At many firms the business case matters most for equity partnership. Committees commonly weigh legal skill, judgment and hours alongside the clients and matters you bring in or grow. Associates usually start with new matters from existing clients, then add a few clients of their own. Ask your practice group leader how your firm sets the standard.
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