How to Onboard a New Client (Step-by-Step Workflow for Accounting Firms)

April 2026 · 10 min read

Client onboarding is where most small accounting firms leak time and lose new clients to first impressions. Sloppy onboarding signals a sloppy firm. A clean, fast onboarding signals competence — and gets you to your first invoice in days, not weeks. This guide is the exact 7-step workflow used by firms that onboard clients in under 2 hours of work spread across 5-7 days.

Why onboarding deserves a system

A new client passes through the same stages every time: enquiry, fit assessment, engagement letter, AML checks, software setup, document collection, first work delivered, first invoice. If you do these ad-hoc — bits in email, bits on the phone, bits in your head — every onboarding takes 2-3x longer than it should and you forget steps for at least one client per quarter.

The fix is a checklist. Always the same. Same sequence. Same documents requested. Same email templates. Onboarding becomes machine-like — which is exactly what you want, because the actual accounting work is where you should be spending your brain power.

The 7-step onboarding workflow

Step 1: Discovery call (30 minutes)

Before anything else, have a 30-minute call with the prospect. Goals: understand their business, decide if they fit your firm, agree the scope, agree the fee. Common reasons NOT to take a client: they want services you don't offer, their business is in a sector you don't want exposure to, they argue about price during the first call, they speak negatively about their previous accountant.

End the call with clear next steps: "I'll send you an engagement letter and a checklist of what we need from you. Please sign and return within 7 days, then we can get started."

Step 2: Send engagement letter (10 minutes)

Use a template — never write engagement letters from scratch. Your engagement letter should specify: services you'll provide, services you'll NOT provide (this is critical for scope creep), your fees and what triggers them, both parties' responsibilities, GDPR data processing terms, complaints procedure, termination terms.

Send it for e-signature, not as an email attachment. E-signature gives you: speed (signed in 24 hours not 7 days), legal robustness (audit trail with timestamp and IP), and a paper-free record. Use this UK engagement letter templateif you don't have one already.

Set yourself a 7-day reminder to chase if not signed. Don't do any work until it's signed.

Step 3: AML and ID checks (20 minutes)

Required by law. Collect ID (passport or photo driving licence), proof of address (utility bill, bank statement, council tax bill — under 3 months), and for company clients, identify beneficial owners (anyone with more than 25%). Document your risk assessment for the client.

Store the ID copies securely — encrypted, NOT in email. See the full AML compliance guide for what your supervisor will look for in an inspection.

Step 4: Set up the client in your software (15 minutes)

In your practice management system: create the client record, link contacts, log the services agreed, set the fee structure, set deadlines for first deliverables (year-end accounts, VAT return, MTD submissions, etc.), assign a primary contact at your firm.

Create the client's portal access at the same time so they can start uploading documents in step 5.

Step 5: Document collection (client's time, then 30 minutes of yours)

Send the client a single email with the client portal link and a clear list of what to upload. The list typically includes: prior year accounts and tax return, current year bookkeeping (or bank statements if no books yet), bank login or open banking authorisation, HMRC online services agent code, payroll records (if applicable), VAT records (if applicable), copy of company formation documents (if Ltd).

The client uploads everything in one go via the portal — no back-and-forth email attachments. As things arrive, tick them off your checklist. Chase missing items after 5 working days.

When everything is in, do a 30-minute review: are records complete? Does anything look unusual or missing? Any red flags for AML? Note anything to ask the client about in step 6.

Step 6: Kick-off meeting (30 minutes)

Before starting work, do a second call to: confirm everything you received is correct, agree priorities for the first 30/60/90 days, walk through how the client will work with you (how to send queries, how often you'll meet, when invoices arrive), set expectations for response time.

This call is short but important. Clients who skip it are 3x more likely to be confused later about what your firm does and doesn't handle.

Step 7: First deliverable + first invoice (varies)

Deliver the first piece of work — even if it's small. A 1-page summary of their year-to-date numbers. A single tidy month of bookkeeping. Anything tangible. Then send the first invoice (or activate the recurring billing). The client now associates your firm with delivery, not just admin.

Onboarding mistakes that cost you clients

• No engagement letter, or sending it as an email attachment. Two weeks later you have no signed contract, no clear scope, and a client who is "just trying you out" rather than committed.
• Asking for documents in 5 separate emails over 3 weeks. Send one email with one comprehensive list. The client will hate getting drip-fed requests.
• Skipping the kick-off call. Saves 30 minutes now, costs hours later when you discover misaligned expectations.
• Storing client ID copies in email. One hacked email account = every client's passport copy compromised. Use encrypted document storage.
• Not invoicing until month 3. If you don't bill in the first 30 days, the client wonders if you're actually doing anything. Even a small first invoice signals progress.

How software cuts onboarding from weeks to days

The single biggest time saver in client onboarding is replacing email with a client portal + e-signature + secure document storage in one tool. FirmFlow handles the firm side of every step above:

• Step 2: send engagement letter for e-signature, signed in 24 hours.
• Step 3: collect ID and address documents via the secure client portal — encrypted at rest.
• Step 4: create the client record with services, fees, and deadline tracking in one screen.
• Step 5: client uploads everything to their branded portal. You see it all in one place.
• Step 7: send the first invoice via Stripe; recurring billing automated from there.

One platform, €29/month flat for up to 5 team members. 14-day free trial.

Onboarding checklist (copy this)

• ☐ 30-min discovery call complete · scope agreed · fee agreed
• ☐ Engagement letter sent for e-signature
• ☐ Engagement letter signed and returned
• ☐ Client ID document collected (passport/driving licence)
• ☐ Proof of address collected (utility bill/bank statement under 3 months)
• ☐ Beneficial owners identified (company clients only)
• ☐ AML risk assessment documented
• ☐ HMRC agent authorisation submitted (form 64-8 or online)
• ☐ Client created in practice management system
• ☐ Deadlines logged (year-end, VAT, MTD, etc.)
• ☐ Client portal access sent
• ☐ Document checklist sent to client
• ☐ All required documents received and reviewed
• ☐ Kick-off meeting held
• ☐ First deliverable produced and shared
• ☐ First invoice sent (or recurring billing activated)

Frequently asked questions