A client onboarding checklist for a UK accounting practice runs in a fixed order: fact-find, AML checks, engagement letter, professional clearance, HMRC and Companies House authorisation, records, software and deadlines. The order matters because the Money Laundering Regulations require identity checks before the relationship starts, and because HMRC authorisation codes take days to arrive. This guide gives the 12 steps, a document list by client type and who can do each step.
A client onboarding checklist for accountants should cover a fact-find, customer due diligence, a signed engagement letter, professional clearance from the previous adviser, HMRC agent authorisation, Companies House access, prior-year records, software set-up, deadline entries, billing set-up, a privacy notice and a welcome call. Complete AML first and treat it as a gate.
Key points
- Verify identity before the business relationship is established (MLR 2017, regulation 30).
- Online agent authorisation codes arrive by post within 7 working days and usually expire after 30 days (GOV.UK).
- Give clients privacy information when you collect their data (ICO: the right to be informed).
- Start the authorisation and clearance requests on day one; they set the pace.
- Most steps are admin that a support team can run, with AML decisions and scope kept in the practice.
Terms used in this guide
- CDD (customer due diligence): identifying and verifying the client and beneficial owners, and understanding the purpose of the work.
- Engagement letter: the written agreement setting out scope, fees and responsibilities.
- Professional clearance: the letter to the previous accountant asking whether there is any professional reason not to accept the appointment, and for handover information.
- Digital handshake: HMRC’s online authorisation request, sent from the agent services account and accepted by the client.
- ACSP: an Authorised Corporate Service Provider registered with Companies House.
The client onboarding checklist: 12 steps in order
- Fact-find. Confirm the client’s structure, the services wanted, year ends, the previous adviser and any deadlines already close.
- AML and identity checks. Verify identity, identify beneficial owners, screen for sanctions and PEPs, and record the risk rating. This is a hard gate.
- Engagement letter. Issue and obtain signature on scope, fees and responsibilities. See our engagement letter template for accountants.
- Professional clearance. Write to the previous accountant. Our professional clearance letter template has wording you can adapt.
- HMRC agent authorisation. Send digital handshake requests or online authorisation codes for each tax.
- Companies House access. Obtain the company authentication code and check each director’s identity verification status.
- Prior-year records. Collect the last accounts and returns, the trial balance, payroll and VAT records, and open queries.
- Software set-up. Add the client to your bookkeeping, payroll and practice management systems; connect bank feeds.
- MTD check. For sole traders and landlords, work out qualifying income and sign up if needed.
- Deadlines and tasks. Enter every filing and payment date in the practice management system.
- Billing. Set up the fee schedule and direct debit, if you use one.
- Welcome call. Confirm contacts, what the client sends and when, and the first deadline.
Steps 5, 6 and 9 depend on the client acting quickly, so start them the same day the engagement letter goes out. A single client onboarding checklist used for every new client, whatever its size, is what makes the order stick.
Who does each step
The table splits the client onboarding checklist between the practice and an admin or outsourced team, with the points where nothing moves until the box is ticked.
| Step | Prepared by | Decided or signed by | Gate? |
|---|---|---|---|
| Fact-find | Admin | Partner or manager | No |
| AML and identity | Admin collects and screens | Partner or MLRO rates risk and accepts | Yes: nothing billable before sign-off |
| Engagement letter | Admin drafts from template | Partner approves scope and fee | Yes: no work before signature |
| Professional clearance | Admin sends and chases | Partner reviews any reply | Yes: clearance issues stop the appointment |
| HMRC and Companies House access | Admin requests and tracks codes | Client accepts | No, but filings wait on it |
| Records, software, deadlines, billing | Admin | Manager checks | No |
| Welcome call | Admin books | Client manager runs | No |
Documents to request by client type
| Client type | Identity and AML | Tax and records |
|---|---|---|
| Sole trader | Photo ID, proof of address | UTR, NI number, last return, bank statements, business records |
| Landlord | Photo ID, proof of address | UTR, NI number, property list with ownership shares, letting agent statements |
| Limited company | ID for directors and anyone with significant control; ownership structure | Company number, authentication code, Corporation Tax UTR, PAYE and VAT references, last accounts and CT600 |
| Partnership | ID for each partner | Partnership UTR, partnership agreement, last partnership return |
For a company, regulation 28 of the MLRs requires its name, registration number, registered office, board members and senior persons responsible for its operations. Our guide to AML checks for accountants explains who should run these checks and what stays with the MLRO.
HMRC and Companies House authorisation
HMRC’s agent authorisation guidance lists the services authorised through the agent services account, including VAT, Capital Gains Tax on UK property and Making Tax Digital for Income Tax. For other taxes, online agent authorisation sends the client a code by post within 7 working days, and the code usually has to be given to you within 30 days. Paper form 64-8 remains available for taxes such as Corporation Tax, PAYE and Self Assessment.
At Companies House, directors and people with significant control now have to verify their identity. Track each one’s status as part of onboarding; our Companies House identity verification checklist sets out the deadlines. Companies House says that from no earlier than November 2026, firms filing for clients will need to be registered as ACSPs (GOV.UK: being an ACSP).
For sole traders and landlords, step 9 is covered in our MTD client onboarding checklist, with the background in our guide to MTD for ITSA.
A sample first-fortnight timeline
The timeline below shows how the client onboarding checklist can run in parallel rather than one step after another. It is illustrative; the client’s speed and HMRC’s post set the real pace.
| When | Practice | Admin team |
|---|---|---|
| Day 1 | Fact-find call | Send ID and document request; start screening as documents arrive |
| Days 2 to 3 | Risk rating and AML sign-off | Prepare CDD file; draft engagement letter |
| Day 3 | Approve scope and fee | Issue engagement letter, clearance letter and authorisation requests |
| Days 4 to 10 | Review clearance reply | Chase signature, codes and prior-year records |
| Days 8 to 14 | Manager checks set-up | Enter codes, set up software and bank feeds, load deadlines and billing |
| By day 14 | Welcome call | Book the call and send the client’s “what to send and when” note |
How to turn this into a client onboarding checklist template
A checklist only works if it lives where the team works. Build it as a task template in your practice management system rather than a document someone has to remember to open. For each step, record four fields: the owner, the date requested, the date completed and a link to the evidence. Mark the gates so the system will not let the next task open until they are ticked.
Keep one master client onboarding checklist and add short variants for client types, such as a landlord or a limited company, instead of separate lists that drift apart. Review the template once a year and after any rule change, such as the Companies House ACSP filing requirement or a new MTD cohort, and note the review date on the template itself.
Common client onboarding checklist mistakes
- Starting work before AML is signed off. The most common and most risky shortcut. Make the AML step a gate in your practice management system.
- Requesting authorisation late. A posted code that expires means starting again, often just before a deadline.
- Chasing documents one by one. Use the document list in your client onboarding checklist: one list per client type, with a portal link and a date.
- No privacy notice. UK GDPR requires privacy information at the point you collect personal data.
- Deadlines kept in someone’s head. Every date belongs in the system on day one.
FAQs
What are the steps in client onboarding for accountants?
The usual order is fact-find, AML and identity checks, engagement letter, professional clearance, HMRC agent authorisation, Companies House access, prior-year records, software set-up, MTD check, deadline entries, billing set-up and a welcome call. AML comes first because the regulations require identity verification before the relationship is established.
What should be on a new client checklist?
Each step above, with the documents needed for the client type, the person responsible, the date requested and the date completed. A good client onboarding checklist also marks gates, such as AML sign-off and the signed engagement letter, so that no billable work starts before they are complete.
How long does client onboarding take?
Usually about two weeks, depending mostly on the client and HMRC. Internal steps can be done in days, but online authorisation codes take up to 7 working days to arrive by post, and clearance replies vary. Starting the authorisation and clearance requests on the first day removes most of the wait.
What should firms evaluate when selecting tax onboarding solutions?
Check that the tool records AML evidence and risk decisions with dates, sends and tracks engagement letters for e-signature, chases documents automatically, integrates with your practice management and tax software, and stores data in line with UK GDPR. Also ask how it handles authorisation tracking, since that is where most delays occur.
Can an outsourced team run our client onboarding checklist?
Yes, for the admin steps: document requests, chasing, screening, drafting letters, authorisation tracking and system set-up. The practice keeps the AML risk decision, the scope and fee, any clearance concerns and client conversations. The team should work inside your systems with logins you issue and can revoke.
Make onboarding consistent
Virtual Service Assists runs the admin side of the client onboarding checklist for UK practices inside your own systems, from first document request to deadlines entered, with every decision left to your team. See our outsourced client onboarding service, or book a consultation to walk through your current process.
