How to Onboard a New Client Without Losing Documents in Email

The typical onboarding process for a new accountancy client involves 15-20 emails, 3 phone calls, and a quiet prayer that nothing important gets lost in between. You send the engagement letter. They email back a photo of it signed on their kitchen table. You ask for ID. They WhatsApp a blurry driving licence. You request bank statements. They arrive three weeks later, attached to a reply to an unrelated email thread, with "here you go" as the entire message body.

It works. Mostly. Until it doesn't — and "doesn't" usually looks like a missing AML check discovered six months in, or a P60 that nobody can find because it's sitting in a former colleague's inbox.

Here's how to do it properly.

Step 1: Before you say yes

Not every prospective client is the right fit. Before you start the paperwork, cover the basics:

• What services do they need? Self assessment only? Full bookkeeping, VAT, year-end accounts, and payroll? The scope determines the fee, the engagement terms, and how much of your time this client will consume.
• Why are they leaving their current accountant? This one matters. "We've outgrown them" is fine. "They kept making mistakes" is worth probing — it might be true, or it might be a client who ignores advice and blames the adviser. "They were too expensive" paired with expectations of a premium service is a red flag.
• Can you actually take them on? Check your capacity. A new limited company client in October when you're already drowning in January deadline work needs careful thought.

Get these answers before you send anything formal. A 15-minute discovery call saves hours of wasted onboarding if the fit isn't right.

Step 2: Engagement letter

Send the engagement letter first. Before you collect a single document. Before you do any work.

This isn't optional — it's a professional requirement. The ICAEW guidance on engagement letters is clear: you need written agreement on the scope of work, fees, responsibilities, and terms before the engagement begins. HMRC won't care that you started working on someone's tax return out of goodwill. If there's a dispute later, the engagement letter is your protection.

Make it easy to sign. E-signatures have been legally valid in the UK for years — there's no reason to be posting letters and waiting for them to come back. Send it digitally, let them sign on their phone, and move on. The fewer friction points, the faster you can get started.

Step 3: AML and identity checks

Anti-money laundering checks are a legal obligation under the Money Laundering Regulations 2017. You must verify your client's identity before you start acting for them. Not during. Not after. Before.

For individuals, that typically means:

• Photo ID (passport or driving licence)
• Proof of address (utility bill or bank statement, dated within the last 3 months)
• A risk assessment documenting your evaluation

For companies, add:

• Companies House confirmation of directors and shareholders
• Verification of persons with significant control (PSCs)
• Enhanced due diligence if the risk profile warrants it

The common mistake is treating AML as a tick-box exercise and filing the documents somewhere vague. "I think Sarah checked the ID" isn't an audit trail. You need a clear record of what was checked, when, by whom, and the outcome of your risk assessment.

Step 4: Collect the documents (without the email chaos)

This is where most firms lose time. You need documents from the client — bank statements, P60s, dividend vouchers, rental income records, whatever's relevant — and the default method is email. Which means:

• Documents arrive piecemeal, across multiple emails, over several weeks
• Some go to one team member's inbox, some to another's
• Nobody's sure whether the full set has arrived
• Three months later, someone needs the bank statements and nobody can find them

The fix is straightforward: give your client a single, clear place to upload everything. A client portal makes this dramatically simpler. The client logs in, sees a list of what's needed, uploads each document, and both sides can see what's been provided and what's still outstanding. No chasing. No "did you get my email?" No hunting through inboxes.

If you're not using a portal yet, at minimum create a checklist for each client type. A sole trader needs different documents than a limited company director. Send the checklist upfront, with clear deadlines, so the client knows exactly what you need and by when.

A practical onboarding checklist

For a typical limited company client, you'll want:

• Signed engagement letter
• AML identity documents (photo ID + proof of address for all directors)
• Previous year's accounts and tax returns
• Agent authorisation forms (64-8 for HMRC, Companies House authorisation)
• Bank statements for the relevant period
• Payroll details (if applicable)
• VAT registration number and recent returns (if applicable)
• Access credentials for bookkeeping software (Xero, QuickBooks, FreeAgent)
• Details of any outstanding queries with HMRC

Don't ask for everything in one email. It overwhelms the client and guarantees that half of it won't arrive. Prioritise: engagement letter and AML first, then agent authorisations, then everything else.

Step 5: Set up your internal records

Once the client has signed and you've completed AML, set up the client file properly in your practice management system. That means:

• Client record with correct entity type, UTR, company number, VAT number
• Relevant tax years and deadlines populated
• Assigned manager and team members
• HMRC agent authorisations submitted (64-8 for self assessment and corporation tax, agent services account for MTD)
• Any notes from the discovery call or handover from the previous accountant

Do this on day one. Not "when things calm down." The longer you leave it, the more likely something gets missed — and the more likely you'll be scrambling to reconstruct information that was fresh a month ago.

Step 6: Confirm and set expectations

Send a brief welcome message once everything is in place. Confirm what you've received, flag anything still outstanding, and set expectations for what happens next. Something like:

"We've got your signed engagement letter, ID verification is complete, and we've submitted the 64-8 to HMRC. We're still waiting on your bank statements for April-September — could you upload those to your portal by Friday? Once we've got those, we'll start on your year-end accounts and aim to have a draft to you within three weeks."

That's it. Clear, specific, and the client knows exactly where things stand. Compare that to the alternative: radio silence for two weeks while you're busy with other clients, followed by a panicked chase when you realise you never got the bank statements.

Making it repeatable

The difference between a firm that onboards smoothly and one that doesn't isn't talent or technology — it's process. The steps above aren't complicated. But doing them the same way, every time, for every client, is what stops things falling through the gaps.

If your current onboarding process involves a lot of "I'll just email them" and "I think we've got their ID somewhere," it's worth spending an afternoon mapping out the sequence. Engagement letter, AML, document collection, internal setup, confirmation. Five steps. Do them in order, track what's outstanding, and you'll stop losing documents in email threads — which, frankly, is a bar that's far too low for 2026.

For firms managing AML and compliance across dozens of clients, having this baked into your practice management system rather than scattered across email, spreadsheets, and shared drives isn't a nice-to-have. It's the difference between confident compliance and a nagging feeling that something, somewhere, has been missed.