A four-partner accountancy practice in Bristol with 380 clients onboards roughly 60 new ones a year. Each onboarding takes between 17 and 24 working days from signed engagement letter to first piece of completed work. Of that, around 11 days is the practice waiting on the client. The other 6 to 13 days is internal: AML checks, software access, information collection, partner sign-off, handover to the assigned manager. The partners cannot work on the client until onboarding is done. The client cannot start to feel value until onboarding is done. Nobody is happy with the lag and nobody has the time to fix it.
This is the recurring pattern across UK practices in 2026. Karbon's 2024 Firm Usage Research shows firms with fully automated practice management save an average of 18.5 hours per employee per week, with onboarding accounting for around a third of those gains.1 Industry research consistently finds workflow automation reducing review cycles by 30 to 40% in practice settings.2 Practice Gateway has documented onboarding-time reductions of 5x for firms moving from spreadsheet-driven intake to automated forms and reminders.3 The numbers are loud. The tooling is mature. And yet most UK practices we speak to still onboard the same way they did in 2018.
Why Onboarding Eats More Partner Time Than Client Work
There is a maths problem at the heart of every accountancy practice. A partner's time is the most expensive resource in the firm, typically charged out at £180–£280 per hour, and a non-trivial chunk of it gets spent on onboarding tasks that are mechanically straightforward.
A typical UK practice onboarding sequence looks like this:
- Engagement letter and proposal. Partner-drafted, partner-sent, partner-chased.
- AML/KYC verification. Partner reviews ID, address, ultimate beneficial ownership where relevant, source of funds for higher-risk engagements. The Money Laundering Regulations 2017 (MLR 2017) put the buck firmly on the firm.
- Information collection. Sending the new client a list of bank statements, prior-year accounts, payroll info, software logins, pension scheme details.
- Software setup. Adding the client to Xero, Sage, BrightPay, Karbon, TaxCalc. Setting permissions. Configuring journals.
- Internal handover. Partner briefs the manager and senior on the client's history, hot spots, and commercial context.
- Kickoff. First call, agreed plan, agreed deliverables, agreed deadlines.
A partner doing all six steps for 60 new clients a year, even at 4 hours each, burns 240 hours. That is six full working weeks of chargeable capacity, roughly £50,000 at a typical UK partner rate. Most of that work is not partner work. It is admin in a suit.
The practices that have got onboarding under control are not the ones with more partners or more admin staff. They are the ones that have moved Steps 2, 3 and 4 off partner desks entirely.
Where Automation Actually Replaces Partner Time
Not every step in the onboarding sequence is a good automation candidate. The frame that consistently works is splitting tasks into three categories: partner judgement (keep), pure admin (automate fully), and partner-shaped admin (automate the surrounds).
Pure judgement, keep. Engagement letter scoping, the AML risk assessment narrative, commercial framing in the kickoff call. These are why the client is paying the partner. Touching them with automation breaks the trust loop.
Pure admin, automate fully. ID verification (Veriff, OnFido, SmartSearch and Credas all integrate with the major UK practice tools), engagement letter sending and chasing (Karbon, TaxDome and Pixie all do this natively), information collection forms (the same), software access provisioning (Xero and BrightPay support this via API), reminder cadence.
Partner-shaped admin, automate the surrounds. Internal handover documents, status dashboards, hot-spot summaries. Generate the document automatically from the captured intake data; the partner reviews and edits rather than authors from scratch.
The Bristol practice in the opening, when they audited their onboarding, found that partners were spending 3.2 hours per onboarding on tasks that were either pure admin or partner-shaped admin. That is 192 partner-hours a year, about £42,000 at their charge-out rate, recovered just by moving the mechanical work to the right people.
The Practice Ops Stack: Karbon, Pixie, TaxDome, Senta
The UK practice management market has settled into a stable set of tools by 2026, and the choice between them is mostly about firm size and workflow philosophy.
Karbon. Strong on collaboration, work-in-progress visibility, and email triage. Used heavily by mid-sized UK practices (5–50 staff). Pricing typically £49–£89/user/month. Onboarding workflows are template-driven and the email-into-task feature is genuinely useful for partners who live in Outlook.
Pixie. UK-built, particularly strong on AML and engagement letter automation, with Companies House and HMRC checks integrated natively. Best for owner-managed practices and small firms (1–10 staff) wanting an opinionated workflow rather than a flexible one. £35–£65/user/month range.
TaxDome. Heavier on the client portal side, popular with tax-heavy practices. Includes e-signatures, payment processing, and document automation. Per-user pricing, similar range to Karbon.
Senta (now part of IRIS). Long-established in the UK market with deep integrations into the IRIS accounts production and tax suite. Best for practices already on IRIS.
The choice between them matters less than the willingness to actually configure the onboarding workflow inside whichever tool you pick. Most firms buy Karbon or Pixie, configure a basic workflow, then never iterate on it. The 18.5-hour-per-week saving is real, but it lives behind another 15 hours of setup work that the partner team needs to invest up front.
That is also where a thin automation layer earns its keep. Karbon, Pixie and TaxDome all cover the standard intake flow well. They struggle at the edges: pulling Companies House officer changes automatically, flagging clients whose AML data is due for refresh under MLR 2017, syncing new clients into a marketing-attribution dashboard. A Make.com or Zapier layer plus a few hours of configuration usually closes those gaps for under £80/month all-in.
What MLR 2017 and ICAEW Practice Assurance Actually Require
The compliance backbone of UK practice onboarding is the Money Laundering Regulations 2017, the Proceeds of Crime Act 2002, and the ICAEW (or other professional body) practice assurance regime. Three points are worth knowing before designing the automated flow.
Customer due diligence under MLR 2017 must be completed before the firm starts working on the engagement, with enhanced due diligence for higher-risk clients (politically exposed persons, complex ownership, cash-heavy businesses). The verification must be evidenced, dated, and retained for at least five years after the relationship ends. Automation does not change this. It makes the evidence trail clean enough to survive a Money Laundering Review Visit without panic.
The ICAEW Practice Assurance regime requires an annual review of risk-assessed clients and a documented procedure for engagement acceptance. Most automated onboarding flows produce this documentation as a by-product, which is a quiet but significant compliance win.
For practices serving clients in scope of Making Tax Digital for Income Tax Self Assessment (mandatory from April 2026 for self-employed and landlords with combined business and property income above £50,000), onboarding pressure is about to spike. Roughly 780,000 taxpayers come into MTD ITSA in the first phase, and the practices that handle them will need to onboard at 3–5x their current volume. Anyone running onboarding manually in 2025 will not survive the 2026 intake wave without doing a Q1 weekend they would rather not.
Setting and Measuring an Onboarding SLA
Most UK practices do not measure onboarding cycle time. They should. The metric that actually drives firm-level economics is engagement-letter-signed to first-work-billable, measured in working days.
The benchmarks worth aiming for in 2026:
- Sub-5 working days for a contractor limited company (mostly mechanical: AML, software access, prior-year reconcile).
- Sub-10 working days for a typical owner-managed SMB.
- Sub-15 working days for a complex group structure or higher-AML-risk client. (For group clients, the bottleneck after onboarding usually shifts to month-end consolidation — see the month-end consolidation stack for multi-entity UK groups.)
Firms hitting these numbers tend to share three habits: a single named owner accountable for the onboarding queue, weekly review of cycle times with the partner group, and a published list of "things we are still waiting on the client for" so chasing becomes structural rather than ad hoc. The technology is the easy part. The discipline of running the queue is the hard part.
If you are an accountancy practice trying to scope what an onboarding automation project looks like for your firm, see what an accounting practice automation engagement typically costs. Most practice onboarding rebuilds happen inside a single 3 to 4 week sprint, with payback in partner-hour recovery usually inside the first three months.
What to Do This Week
Pull your last twelve onboardings out of whatever system you currently use and write down two numbers per client: working days from signed engagement letter to first deliverable, and rough partner hours spent on the file before client work started. The mean of the second number is the salary you are paying for onboarding admin. The mean of the first number is the gap between the client signing and feeling like they hired the right firm. Both numbers move the same way once the workflow is built. The firms that fix onboarding first are also the firms whose partners are visibly less tired by Christmas, which, in an industry that defaults to working harder rather than working differently, turns out to be a competitive advantage worth more than the hours alone.
Sources
1. Karbon, "Practice Management Software for Accounting Firms" — 2024 Firm Usage Research cited on the product homepage. karbonhq.com.
2. ICAEW, "Automating the Accounting Practice." Overview of automation impacts and review-cycle improvements in UK practices. icaew.com.
3. Practice Gateway, "Reduce onboarding time by 5x." Vendor documentation of onboarding-time reductions for firms moving from spreadsheet-driven intake. practicegateway.com.
