No engagement letter before acceptance
Client acceptance is an approval assigned from the engagement partner field. The checklist halts until it is Approved, so the letter and authorisation requests cannot run ahead of due diligence.
Accounting Firm Client Onboarding Checklist Template
New clients arrive with a deadline attached. Starting work before the due diligence, the engagement letter or the authority to act is in place is where most onboarding problems begin.
This free accounting firm client onboarding checklist is for accounting, bookkeeping and tax practices in the UK and the US. One run takes a new client from enquiry to the first working month: conflict check, due diligence and a risk rating, the partner’s decision to accept, the engagement letter, authority to act with HMRC or the IRS, professional clearance and handover, systems setup, kickoff and sign-off. A jurisdiction question shows the UK or US tasks, and two more add handover and payroll work only when they apply.
Three Questions Before the First Job
A generic onboarding checklist is about a good first impression. An accounting practice also has to answer three questions a software vendor never faces. Should we act for this client at all? May we act for them with the tax authority? Are we ready to work without inheriting someone else’s mistakes? Each answer needs evidence a supervisor or insurer may ask to see.
The checklist follows that order. Nothing is promised until the firm accepts the client, and nothing is filed until authority and prior-year records are in place. For a returning client who only needs a return, the Tax Season Client Intake Checklist is enough.
Should we act?
Acceptance
Covers: conflicts, capacity, due diligence, the risk rating and the partner’s decision.
Evidence: identity and ownership records, screening results and a dated approval.
May we act?
Authority
Covers: the engagement letter, HMRC agent authorisation or IRS Forms 8821 and 2848, and payroll authority.
Evidence: the signed letter and each authorisation showing as active.
Are we ready?
Readiness
Covers: clearance, the prior-year handover, systems, the deadlines calendar and kickoff.
Evidence: the handover file, inherited deadlines with owners, and sign-off.
What the Accounting Firm Client Onboarding Checklist Covers
Seven phases run from enquiry to a signed-off client. The jurisdiction answer shows the UK or US tasks, Phase 5 appears only for a client switching accountants, and the payroll tasks appear only when payroll is in scope. Acceptance and final sign-off are approvals that halt the checklist.
Scope
Phase 1: Enquiry & Scope
Owned by the client manager. Scope DropDowns: Jurisdiction (UK / US), Is the client switching from another accountant? (Yes / No), Does the engagement include payroll? (Yes / No).
- Name the engagement partner, client manager, compliance lead and payroll lead — later tasks and both approvals are assigned from these fields
- Answer the scope questions — UK or US, is the client switching from another accountant, and does the engagement include payroll
- Record what the client needs and why now — services, entity type, year end and deadlines already in sight
- Run the conflict check — against existing clients, connected parties and the other side of any dispute, sale or divorce
- Confirm the firm can do the work — skills, capacity before the first deadline, and no work the firm is not licensed for
- Quote the fee — from the scope recorded here, with exclusions written down
Due diligence
Phase 2: Client Due Diligence
Assigned to the compliance lead. The register and screening tasks show for UK clients and the OFAC task for US clients. The risk rating is a DropDown (Low / Medium / High); High shows the enhanced due diligence task.
- Verify the identity of the client and anyone acting for them — documents or an electronic check, completed before the business relationship starts
- Identify the beneficial owners — for companies, partnerships and trusts, who owns or controls the client and how, verified on a risk basis
- Check the PSC register and report material discrepancies — to Companies House under regulation 30A; shown for UK clients
- Screen for politically exposed persons and sanctions — the client, directors and beneficial owners; shown for UK clients
- Screen against the OFAC sanctions lists — US sanctions apply to every US person and business; shown for US clients
- Rate the client’s risk — Low, Medium or High, with reasons: the business, source of funds, services and red flags
- Carry out enhanced due diligence — shown only when the rating is High: more evidence, senior approval and closer monitoring
Engage
Phase 3: Accept & Engage
The acceptance approval goes to the engagement partner and halts the checklist until it is Approved, so no engagement letter goes out first. The section 7216 task shows for US clients.
- Engagement partner approval of client acceptance — conflicts, due diligence and the risk rating reviewed, with the decision recorded
- Draft the engagement letter — scope, client responsibilities, fees, liability, termination and data protection, following your professional body’s guidance
- Collect any section 7216 consents you need — written consent before using or disclosing return information beyond preparing the return; shown for US clients
- Send the privacy notice — what personal data the firm holds and why
- Get the signed engagement letter back — attached to this task before any chargeable work starts
- Set up billing — payment terms, fee schedule and how the client pays
Authorise
Phase 4: Authority to Act
The first four tasks show for UK clients and the last three for US clients, from the Jurisdiction answer in Phase 1.
- Request agent authorisation from the agent services account — one request per tax; the client has 21 days to accept the link
- Confirm each authorisation is active — check the client list in the account and resend any link that expired
- Check whether Making Tax Digital for Income Tax applies — sole traders and landlords over the qualifying income threshold; authorise as main or supporting agent
- Check Companies House identity verification — directors and PSCs of company clients verified, or the firm verifies them as an authorised corporate service provider
- Get Form 8821 or Form 2848 signed — 8821 to receive the client’s information, 2848 to represent them; submit online or request it through Tax Pro Account
- Confirm the authorisation is on the CAF — it shows in Tax Pro Account once the client approves it in their own online account
- Collect state authorisations — each state where the client files uses its own power of attorney form
Handover
Phase 5: Professional Clearance & Handover
Shown only when “Is the client switching from another accountant?” is Yes. Owned by the client manager.
- Get the client’s written permission to contact the previous accountant — confidentiality stops them discussing the client without it
- Write to the previous accountant — in the UK, a professional enquiry asking whether there is any professional reason not to act; in the US, a records request with the consent attached
- Follow up a slow reply in writing — say the firm will accept the appointment unless it hears by a set date
- Request the handover records — last returns and accounts, trial balance, fixed asset register, losses and elections carried forward, payroll records
- Separate the client’s records from the predecessor’s working papers — the client gets its own records; working papers usually stay with the firm that made them
- Log inherited deadlines and open correspondence — HMRC enquiries, IRS notices and anything due soon, each with an owner
Setup
Phase 6: Systems & Records Setup
The last three tasks show only when “Does the engagement include payroll?” is Yes, and are assigned to the payroll lead.
- Set the client up in your practice and accounting software — entity details, year end, tax references and services
- Connect bank feeds and ledger access — named user accounts rather than shared logins, read-only where that is enough
- Build the deadlines calendar — returns, payments, VAT or sales tax, filings and estimated payments, each with an owner and a reminder
- Bring the client’s data under your security plan — secure portal, access limited to the team and, in the US, the written information security plan
- Collect the payroll data — employees, pay rates, schedules, year-to-date figures, benefits and pension or retirement plans
- Get payroll authority — PAYE agent authorisation with HMRC, or Form 8655 in the US if the firm files and deposits as reporting agent
- Run a test payroll — compare it with the previous provider’s last run before going live
Kickoff
Phase 7: Kickoff & Sign-Off
The final sign-off is an approval for the engagement partner and halts the checklist until it is Approved.
- Hold the kickoff meeting — introduce the team, the scope, the deadlines and the client’s monthly tasks
- Send the first document request — what you need, by when, through the portal
- Agree how you will work together — named contacts, response times and how records arrive
- Set the due diligence review date — sooner for higher-risk clients, so ongoing monitoring happens on a schedule
- Book the 30-day check-in — to fix friction before the first deadline
- Engagement partner sign-off that onboarding is complete — due diligence, engagement letter, authorisations and handover all on file
UK and US Onboarding Obligations Side by Side
The biggest difference is anti-money laundering. UK accountants and tax advisers are in the regulated sector, so client due diligence is a legal duty. US accountants are generally not covered by the Bank Secrecy Act’s AML programme rules, though sanctions law applies to everyone. Rules change, so check the current guidance from HMRC, the IRS and your professional body; this is a starting point, not legal advice.
| Area | UK | US | Phase |
|---|---|---|---|
| Client due diligence | Required under the Money Laundering Regulations 2017, as amended; verify identity before the relationship is established | No general AML programme duty; e-file rules still expect you to confirm who your clients are | 2 |
| Beneficial owners | Identify and verify them; report material discrepancies with the PSC register | No onboarding duty for accountants; good practice to know who controls the client | 2 |
| PEPs and sanctions | Enhanced due diligence and senior management approval for politically exposed persons | OFAC sanctions apply to all US persons and businesses | 2 |
| Who supervises | Your professional body (such as ICAEW, ACCA, AAT or ICAS) or HMRC; the government plans to move this to the FCA | No AML supervisor; practice before the IRS is governed by Circular 230 | – |
| Authority to act | Agent authorisation per tax through the agent services account; the firm must register with HMRC as a tax adviser | Form 8821 or 2848 on the Centralized Authorization File; Form 8655 for payroll; state forms | 4, 6 |
| Change of accountant | Professional enquiry to the existing accountant with the client’s permission (ICAEW Code section 320 and equivalents) | Client consent before the predecessor shares information; Circular 230 requires client records returned on request | 5 |
| Records and data | Keep due diligence records five years after the relationship ends; UK GDPR applies | A written information security plan under the FTC Safeguards Rule; IRS Publication 5708 is a template | 2, 6 |
Several of these changed recently. HMRC began phasing in mandatory registration for paid tax advisers on 18 May 2026; firms with an agent services account do not register again but may be contacted. Amendments to the Money Laundering Regulations largely took effect on 30 June 2026. Companies House identity verification began on 18 November 2025, and Making Tax Digital for Income Tax started in April 2026 for sole traders and landlords with qualifying income over £50,000.
In the US, the FTC Safeguards Rule treats tax preparers as financial institutions and, since May 2024, requires notice to the FTC within 30 days of discovering a breach of unencrypted information about 500 or more people.
Why Onboard Accounting Clients in CheckFlow?
One template for UK and US clients
The jurisdiction DropDown shows HMRC or IRS tasks, a High risk rating adds enhanced due diligence, and handover and payroll tasks appear only when they apply.
A file you can show a supervisor
Identity documents, screening results and the signed letter sit on the tasks that required them, and the audit trail records who approved what and when. Due diligence reviews can run as a recurring checklist.
CheckFlow is not practice management, accounting or tax software, and it does not perform identity checks. It runs the process around those tools so every new client goes through the same steps. See how firms use it for client onboarding and across professional services.
After onboarding, the Monthly Bookkeeping Checklist runs the monthly close, and clients can keep their own records in order with the Tax Preparation Checklist. When a relationship ends, the Client Offboarding Checklist covers the handover in the other direction.
Frequently Asked Questions
What should an accounting firm’s client onboarding checklist include?
A conflict check, due diligence with a risk rating, a recorded acceptance decision, a signed engagement letter, authority to act with the tax authority, professional clearance and handover when the client is switching firms, systems setup, a deadlines calendar and a kickoff. Payroll setup and enhanced due diligence are added when they apply.
Do accountants have to carry out anti-money laundering checks on new clients?
In the UK, yes. Accountants, bookkeepers and tax advisers are in the regulated sector under the Money Laundering Regulations 2017 and must carry out customer due diligence, assess risk and keep records for five years after the relationship ends. US accountants are generally not subject to the Bank Secrecy Act’s AML programme rules, but OFAC sanctions apply to every US business.
Can we start work before due diligence is complete?
In the UK the default is no: identity must be verified before the business relationship is established. Regulation 30 allows verification during establishment only where that is necessary not to interrupt the normal conduct of business, the risk is low, and verification is finished as soon as practicable. Record the reason if you rely on it.
What is professional clearance and is it required?
It is the common name for the enquiry an incoming UK accountant sends the existing one, asking whether there is any professional reason not to accept the appointment. ICAEW points out that no firm can give or withhold clearance as such. The existing accountant needs the client’s permission to reply; if none comes in a reasonable time, write again saying you will accept unless you hear by a set date.
How do we get authorised to deal with HMRC or the IRS for a new client?
For HMRC, most authorisations are requested from the agent services account: the client gets a link to accept within 21 days, one tax at a time. For the IRS, Form 8821 lets you receive a client’s information and Form 2848 lets you represent them. Tax Pro Account sends the request to the client’s IRS online account, and it shows as soon as they approve it.
Is CheckFlow free for this template?
14-day free trial, no card required. The Business plan is $10 per user per month after the trial. Full details at checkflow.io/pricing.