C · Client onboarding & engagement
Client Onboarding Checklist for Accountants
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Quick answer
A thorough accountant onboarding process covers professional clearance, AML identity checks, risk assessment, an engagement letter, HMRC and Companies House authorisation, data collection, fee agreement and a welcome communication. Doing these consistently for every client, in a fixed order, reduces AML risk and stops work starting before the file is compliant.
Key takeaways
- Onboarding is not just paperwork — it sets the tone for the whole client relationship.
- AML identity verification and risk assessment must happen before you begin substantive work.
- Use a fixed checklist so nothing is missed under time pressure with a new client.
- HMRC and Companies House authorisations often take days to activate, so start them early.
- A short welcome pack reduces early support queries and clarifies how the client should contact you.
Why does client onboarding need a fixed process?
A consistent checklist prevents compliance gaps, speeds up new client setup, and gives clients a professional first impression of your practice.
New practice owners often onboard the first few clients informally, then discover gaps later — a missing engagement letter, an AML file with no risk assessment, or an authorisation that was never actually completed. A written checklist, followed the same way every time, closes those gaps and makes the process easier to delegate to a team member as you grow.
What are the steps in a client onboarding checklist?
A typical sequence runs from initial enquiry and clearance through to identity checks, engagement letter, agent authorisation, data collection and a formal welcome.
- Initial enquiry and scoping call to confirm services and fit
- Professional clearance letter to the previous accountant, if applicable
- Client due diligence: identity verification for individuals, and for companies, identification of the entity and its beneficial owners
- Firm-wide and client-specific AML risk assessment, setting the risk level and review date
- Proposal or fee quote agreed and signed
- Engagement letter issued, covering scope, fees and terms of business, and signed by the client
- HMRC agent authorisation requested for the relevant taxes (SA, CT, VAT, PAYE)
- Companies House authentication code or ACSP identity verification arranged, where filings are needed
- Data collection: prior year accounts, bookkeeping records, payroll data, passwords or access to existing software
- Welcome communication confirming main contacts, how to reach the practice, and key deadlines coming up
What ID and AML checks are needed before you start work?
You need to verify the identity of individual clients and, for companies, the entity plus its beneficial owners, then record a risk-based assessment before or very shortly after starting work.
For individuals, a passport or driving licence plus proof of address is standard. For limited companies, verify the company at Companies House, then identify directors and anyone owning or controlling more than 25% of shares or voting rights. Higher-risk clients — cash-intensive businesses, those with complex ownership structures, or connections to higher-risk jurisdictions — need enhanced due diligence, which might mean additional documents or ongoing monitoring.
Retention
Keep client identification and supporting records for five years after the business relationship ends, in line with the Money Laundering Regulations 2017.
When should the engagement letter be signed relative to starting work?
Ideally before any chargeable work begins, so scope and fees are agreed in writing and both parties know what is and is not included.
It is tempting to start urgent work — a looming filing deadline, say — before paperwork is finalised. Where you genuinely must, send the engagement letter alongside a short covering note confirming the scope you are acting on provisionally, and get it signed as soon as practically possible afterwards.
What client data should you collect during onboarding?
Prior year accounts and returns, bookkeeping records or software access, payroll data if relevant, and a note of key contacts and preferred communication methods.
| Client type | Key data to request |
|---|---|
| Limited company | Last filed accounts, CT computations, share register, PSC details, bookkeeping software access |
| Sole trader/partnership | Last SA return, business bank statements, mileage and expense records |
| Payroll client | Year-to-date payroll figures, pension scheme details, employee starter/leaver information |
| VAT-registered client | VAT scheme, last returns filed, partial exemption details if applicable |
What should a client welcome message include?
Confirm who the client's main contacts are, how to reach the practice, what happens next, and any upcoming deadlines they should be aware of.
- Named contact and their direct email or phone number
- How to submit records or use the client portal
- Upcoming deadlines relevant to their business
- What to expect and when (e.g. draft accounts turnaround time)
- Out-of-scope items and how additional work is charged
How to onboard a new accountancy client
- 1
Scope the engagement
Confirm services, complexity and pricing on an initial call before quoting.
- 2
Seek professional clearance
Write to the previous accountant if one is being replaced, and wait a reasonable period for a response.
- 3
Carry out client due diligence
Verify identity for individuals and beneficial owners for companies, and record a risk assessment.
- 4
Issue and sign the engagement letter
Set out scope, fees and terms of business before substantive work starts.
- 5
Request HMRC agent authorisation
Apply for authorisation for each relevant tax through your Agent Services Account.
- 6
Arrange Companies House access
Confirm authentication codes or ACSP identity verification needed for filings.
- 7
Collect prior records and data
Gather last year's accounts, bookkeeping access, payroll data and any outstanding matters.
- 8
Set up the client on your systems
Add the client to your practice management software with deadlines and recurring tasks.
- 9
Send a welcome communication
Confirm contacts, portal access and next steps in writing.
- 10
Review after 30 days
Check nothing is outstanding from onboarding before treating the client as fully live.
How Remindoo helps
Remindoo's client onboarding automation lets you turn this checklist into a repeatable template: standardised onboarding requests, checks and first services fire automatically when a new client is added, so nothing depends on someone remembering the full list. AML checks, risk levels and review notes sit directly on the client record, alongside the tasks and subtasks needed to complete identity checks, engagement letters and authorisations, each with its own status. Because the client record also syncs with Companies House and keeps a full timeline and notes, your onboarding history stays visible in one place rather than scattered across email threads, making it far easier to prove your process was followed if a regulator or professional body ever asks.
Frequently asked questions
How long should client onboarding take?
Most straightforward clients can be fully onboarded within one to two weeks, though HMRC authorisation and clearance responses can extend this.
Can I start work before onboarding is complete?
You should complete identity checks and risk assessment before starting substantive work; the engagement letter should also ideally be signed first.
Do sole traders need the same onboarding process as companies?
The principles are the same, though company clients need additional steps for beneficial ownership checks and Companies House authorisation.
What's the biggest onboarding mistake new practices make?
Skipping or delaying the AML risk assessment because it feels like paperwork rather than urgent client work, which creates compliance gaps.
Should onboarding differ for high-risk clients?
Yes, apply enhanced due diligence and more frequent review for clients assessed as higher risk under your firm-wide risk assessment.
Is a client portal necessary for onboarding?
It is not compulsory, but a portal makes secure document collection and progress tracking considerably easier than email.
How do I onboard several clients at once after buying a fee block?
Use the same checklist per client but batch tasks like clearance letters and authorisation requests to work through efficiently.
Start your free Remindoo trial
Set up deadlines, onboarding and workflows for your new practice with a 60-day free trial.
Sources
Last updated 23 September 2026. General guidance, not legal or regulatory advice. Check with your professional body.
