The order client onboarding actually has to happen in

The short answer

For a UK accountancy practice, client onboarding isn't just admin, it's a set of steps that have to happen, roughly in order, before chargeable work can properly start: anti-money laundering checks, professional clearance from any previous accountant, an agreed engagement letter, and the access that lets you actually file anything (HMRC authorisation, Companies House, bank feeds). None of it can be skipped to save time. What can change is whether someone chases each step from memory, or a system tracks it and nudges whoever's waiting.

The order onboarding has to happen in

A new client doesn't arrive needing one thing done. They arrive needing several things done in roughly the right sequence, and doing them out of order tends to create rework. Broadly:

1. Initial checks and client due diligence, before anything substantive begins.
2. Professional clearance from the client's previous accountant, where one exists.
3. An agreed, signed engagement letter setting out scope and terms.
4. Practical access: HMRC agent authorisation, Companies House authentication, bank feeds and software.
5. Deadlines set from day one, not discovered later.

Getting this order roughly right matters more than getting every individual step perfect, because a late engagement letter or a missed authorisation step tends to stall everything behind it.

Before any work: engagement letter and client due diligence

Client due diligence under the Money Laundering Regulations has to happen before you properly take someone on, not as a formality fitted in afterwards. In general terms, that means verifying who the client actually is, understanding the purpose of the relationship and where funds are expected to come from, and keeping records of what you checked and when. The specifics, including how long records need to be retained, are set out in current government guidance rather than something worth quoting an exact figure for here, since it's the kind of detail that gets updated. Check the current position on gov.uk's money laundering regulations guidance or your supervisory body (ICAEW, ACCA or AAT) rather than relying on a figure from a blog post, including this one.

An engagement letter needs to go out and be agreed before chargeable work properly begins too. The letter itself is rarely the hard part, most practices have a template. The hard part is remembering to trigger a new one for a new client, a new service, or a scope change partway through the relationship, and keeping a record of what was sent and when.

Professional clearance and HMRC agent authorisation

If the client is moving from another accountant, professional clearance is the step most easily forgotten under pressure to get started. It's a courtesy between practices as much as anything else, asking the previous accountant whether there's any professional reason not to act, and it's worth doing properly rather than skipping because the client is keen to move quickly.

Alongside that sits HMRC agent authorisation, the process that lets you actually act and file on a client's behalf. It typically takes a little time to come through, which is exactly why it's worth starting early rather than discovering a deadline is close and you're still waiting on authorisation to clear.

Getting access: bank feeds, software and Companies House

The practical access side rarely gets attention until it's blocking actual work. A new client usually needs: a bank feed connected into your accounting software, access set up in whatever platform you both use (Xero, QuickBooks or similar), and for a limited company, a Companies House authentication code if you're going to file on their behalf. Each of these is a small task on its own. Collected together and chased by memory across a dozen new clients a year, they're a meaningful chunk of the admin that eats a practice's evenings.

Setting deadlines from day one

VAT quarters, the 31 January personal tax deadline and the staged rollout of Making Tax Digital for Income Tax Self Assessment all arrive on fixed dates regardless of how far behind onboarding has fallen. The fix isn't working faster later, it's capturing every relevant deadline for a client the moment they're onboarded, not weeks afterwards once the paperwork settles. Our guide to Making Tax Digital software covers what compatible software actually needs to do here.

Turning the checklist into stages someone can see

A checklist in someone's head, or buried in an email thread, fails quietly. The same checklist as visible stages, identity check done, professional clearance requested, engagement letter sent, agent authorisation live, access confirmed, deadlines logged, lets a partner glance at a client and know exactly what's outstanding, without checking an inbox, a spreadsheet and asking a colleague.

When to get help, and what we'd do

This is exactly what our crm-setup work does: a CRM or practice workspace set up around these actual stages, not a generic pipeline that doesn't match how onboarding really happens in a UK practice. Alongside it, auto-simple sets up a single automated reminder for whichever step most often stalls, usually chasing outstanding documents or a slow-to-arrive agent authorisation, so it happens on schedule rather than when someone remembers. For the automation side specifically, see our guide to how to automate client onboarding, and for the wider picture of why this all matters, our page on admin eating your evenings.