Client onboarding is the single most important workflow in an accounting practice. Done well, it sets up a profitable, low-friction relationship that compounds over years. Done badly, it produces compliance gaps, billing disputes, and a slow drip of remedial work that erodes margin for the lifetime of the engagement.
This guide steps through the onboarding process used by well-run UK firms in 2026, from the initial enquiry through to a settled relationship at the 90-day mark. It is opinionated about what good looks like, and it is structured so that you can lift any single step into your own playbook without redesigning the whole process.
Step 1: Initial enquiry and fit assessment
The first conversation is not about price. It is about fit. The questions that matter at this stage are about the prospect's entity structure, turnover band, sector, service expectations, software stack, and the reason they are leaving their current adviser.
A fifteen minute call is usually enough to determine whether the prospect fits the firm's ideal client profile. If they do not, decline politely and refer them on. The cost of taking on a poor fit is high and persistent; the cost of declining one is a single email.
Step 2: Initial risk screening
Before issuing a proposal, run a desk-based risk assessment. The check should answer four questions: is the entity real and registered as claimed; are any controllers on a sanctions or PEP list; is the sector or geography inherently elevated risk; and are there any adverse media flags that warrant senior review.
In 2026, an integrated practice management platform can complete this screen in under five minutes by combining Companies House data, sanctions screening, and adverse media in a single workflow. The output is a preliminary risk rating that determines how heavy the rest of the onboarding needs to be.
Step 3: Proposal and engagement letter
The proposal should specify scope, deliverables, exclusions, fee basis, payment terms, and the period of engagement. The engagement letter then formalises these terms together with the regulatory clauses required by your professional body - limitation of liability, complaints handling, data protection, conflicts of interest, and the right to cease acting.
A fixed-fee model with clearly delineated scope changes is overwhelmingly the modern norm. Hourly billing without a scoping document is a recipe for fee disputes. Whichever model you adopt, write down the assumption set that supports the fee so that scope variations are obvious when they occur.
Step 4: KYC and beneficial ownership
No work begins until KYC is complete. The standard documentary set for a limited company client is:
- Certificate of incorporation and current articles of association
- Companies House confirmation of registered office and directors
- Identification and address verification for each director and each beneficial owner (over 25% ownership or control)
- A current organisation chart for groups, including any non-UK entities
- A description of the source of funds for the business
- Sanctions, PEP, and adverse media screening output
- A signed client risk assessment from the engagement partner
- A copy of the most recent prior-year accounts and tax filings where available
Step 5: Professional clearance
Where the client has been previously advised, professional clearance from the outgoing accountant is a courtesy expected by every UK professional body. The letter requests confirmation of any professional reasons that should prevent the new firm from accepting the engagement, plus the transfer of working papers necessary to complete the next set of accounts and returns.
Best practice is to write the clearance letter on the same day the engagement letter is signed, and to follow up by phone if no response is received within ten working days. Silence after a follow-up is rare but, when it occurs, the file should record both attempts and the engagement partner's decision to proceed.
Step 6: Authorities, agent codes, and software setup
Once professional clearance is in hand, the administrative setup begins. This includes obtaining agent authorisations for self-assessment, VAT, PAYE, and Corporation Tax via the Agent Services Account, adding the client to the firm's practice management platform, setting up bookkeeping access (Xero, Zoho Books, or whichever platform the client uses), and configuring secure document exchange through the client portal.
A frequently overlooked detail is naming conventions. Set the standard for how client records are named, how bookkeeping ledgers are configured, and how documents are filed, at this stage - not after six months of accumulated drift.
Step 7: Kick-off meeting
The kick-off meeting brings the client, the engagement partner, and the assigned manager together to align on expectations. The agenda should cover the calendar of deliverables for the year, who the client should contact for what, the cadence of management reporting (if any), and how to handle ad-hoc questions.
A well-run kick-off is a strong predictor of long retention. It sets a tone of professionalism, demonstrates the firm's systems, and gives the client confidence that they have made the right choice in switching.
Step 8: First 30 days
In the first 30 days, the firm should complete a baseline review of the client's books, surface any prior-year carry-forward issues, and confirm that scheduled deliverables are in the practice management system with appropriate owners. Any data quality issues found in the baseline review should be flagged in writing to the client at the end of week four.
The 30-day check-in is also the moment to review the initial risk assessment in light of what you have actually seen. If the client's position is materially different from what was described at proposal, scope and fee should be re-discussed promptly, not at year-end.
Step 9: 90-day review
The 90-day mark is the right time for a partner-level review of the engagement. Are deliverables tracking on time? Is the fee model still appropriate? Are there cross-sell opportunities (R&D claims, payroll, tax planning) that emerged in the first quarter? Is the client engaging well with the portal and the firm's communication channels?
Many firms find that a documented 90-day review prevents the slow accumulation of small problems. It also signals to the client that the relationship is being actively managed rather than left to autopilot.
Common onboarding pitfalls
A handful of recurring mistakes account for most onboarding pain. KYC documents are accepted without being verified against an independent source. Engagement letters are signed but not countersigned by the firm. Agent authorisations are requested but not chased when the digital handshake fails silently. Professional clearance is sent but the outgoing firm's response is filed without being read.
A simple antidote is to insist that the onboarding checklist is signed off in the practice management system before the client is moved to active status. If a step is missing, the workflow stops - and the right person is alerted to resolve it.
How Accupe streamlines onboarding
Accupe consolidates onboarding into a single workflow. Companies House lookup auto-populates company data; OpenSanctions screening runs in seconds; KYC documents are collected through the encrypted client portal; e-signatures handle the engagement letter without a DocuSign subscription; and Smart Boards track every onboarding milestone from initial enquiry to 90-day review. Compliance Radar gives the partner-level overview of risk across the new portfolio. The cumulative effect is a defensible, audit-ready file from day one, without bouncing between four different tools.