Client onboarding process: a step-by-step guide for accounting, legal and advisory firms

Client onboarding is everything that happens between a client saying yes and your team doing the first real piece of work. For accounting, legal and advisory firms that usually means contracts, identity checks, documents and system access, all before you can start.

Good onboarding feels organized to the client. They know what you need, why you need it and what happens next. Inside the firm, nobody has to guess which step comes next or who owns it.

The steps below follow the order most firms use. Adapt them to your practice, but keep the order the same for every client so nothing gets skipped.

The engagement letter defines the scope, the fees, who is responsible for what and how the relationship can end. Send it the same day the client accepts your proposal, while their attention is on you.

Be specific about scope. A letter that says "bookkeeping" invites disputes later. One that says "monthly bank reconciliation for two business accounts and a quarterly sales tax return" sets clear expectations.

Do not start work until the letter is signed. Use whatever signing method your firm already trusts, and file the signed copy with the client record.

Many accounting, legal and advisory firms must verify who their client is before acting for them, under anti-money-laundering or professional rules. Requirements vary by country, regulator and type of client, so confirm the current rules that apply to your firm.

For individuals, this usually means a photo ID and a recent proof of address. For companies, expect a certificate of incorporation, a list of directors and beneficial owners, and identity documents for each of those people.

Check expiry dates and image quality when the documents arrive. A passport photo with glare across the name, or a proof of address older than 3 months, will have to be requested again, and that delays every step after it.

After identity, you need the documents to do the work: prior year returns, bank statements, contracts, payroll reports or the case file. Ask for them in one checklist rather than a series of emails, so the client can see the full scope at once.

Tailor the checklist to the engagement. A new bookkeeping client might need 12 months of bank statements, the last filed accounts and a list of open invoices. A law firm taking on a property matter might need the purchase contract, title documents and the mortgage offer.

Give each item an instruction and an example, and use one secure upload link instead of email attachments. DocAsker covers this step: the client gets one link with the checklist, AI checks every upload for quality, document type, dates, signatures and missing pages, and reminders go out until the list is complete.

Most engagements need access to something the client controls: accounting software, a payroll portal, a tax authority account or a bank feed. List exactly which access you need and how the client grants it, ideally with short steps or screenshots.

Ask clients to invite you as a user rather than share their own password. That keeps an audit trail and lets them remove your access when the engagement ends.

On your side, create the client record, folder structure and billing setup before the kickoff. Use the same folder structure for every client so anyone on the team can find a file.

The kickoff meeting is where the client meets the people doing the work. Keep it to 30 to 45 minutes and send an agenda in advance.

Use it to confirm scope and deadlines, walk through any documents still outstanding, agree how and how often you will communicate, and name one contact on each side. Close with a written summary of who does what by when.

The first deliverable shows the client what working with you is like. Choose something you can complete soon after kickoff, such as a cleaned-up bank reconciliation, a first draft or a short findings memo.

Explain what you did and what comes next. A short note covering the result, any open questions and the next date in the calendar is enough. This is also a good moment to ask how onboarding went and to fix anything that was unclear before the next client.

Automate the steps that are the same every time and do not need judgment. Keep people on the steps where a client needs to talk to someone or where a decision is required.

A simple test: if a step is a copy-paste email, a reminder or moving a file into a folder, automate it. If it involves interpreting a document, agreeing scope or reassuring a client, keep a person on it.

The most common mistake is starting work before the basics are done. Work started without a signed engagement letter or completed identity checks creates risk for the firm and often has to be redone.

The second is asking for documents in pieces. Each extra email costs the client attention and makes the firm look disorganized. Vague requests, like "bank statements" with no period, cause the same problem with more back-and-forth.

Finally, many firms keep the process in one person's head. When that person is busy or away, steps get skipped. Write the process down, use the same checklist for each client type, and review it once a year.