A zero WIP, zero debtors practice bills its recurring work before or as it's done and collects the fee automatically, so very little money is ever waiting. No practice with real clients gets to exactly zero. As a direction, though, it's a clear target: it needs no benchmark, and it means the same thing however you measure lock-up.
In this article
The short version
- Zero WIP and zero debtors means billing recurring work in advance and collecting it automatically.
- Monthly fixed fees collected by direct debit remove most of the wait for recurring work.
- Zero needs no benchmark and means the same however you measure lock-up.
- One-off work, advance-fee refunds, VAT timing and clients who won't use direct debit set the limits.
- Writing work off lowers WIP but loses the fee, so track write-offs alongside lock-up.
What zero WIP and zero debtors looks like
In most practices, lock-up builds in two places. Work in progress (WIP) is time recorded and not yet billed, and it sits there until someone decides to raise the fee note. Debtors are fee notes sent and not yet paid, and they sit there until the client gets round to it.
The zero model removes both waits for your recurring work. A client on a fixed monthly fee is billed on the same date each month, usually at the start, so the fee note goes out before most of the work is done and there's no WIP to carry. The fee is collected by direct debit on a date you've chosen, so there's usually nothing to chase.
What's left is the work that can't be priced in advance: one-off advisory projects, extra work outside the agreed scope, disbursements. Those still create WIP and debtors, but they're a smaller share of your fees, and you can bill them as they happen.
Why aim for zero and not a number
Most lock-up targets need something to compare with. The most useful published reference for UK practices is a NatWest survey of 23 accountancy firms from 2024. It's a helpful sense check, but it's a small sample, and the figure moves with every choice about what counts as WIP.
Zero doesn't need a comparison. You don't need to know what other practices carry to see whether you're carrying less than last quarter. It also gets round the definitional arguments that make lock-up figures hard to compare: whether unbilled disbursements count, whether WIP is valued at charge-out rates or at cost, and whether you quote days or a percentage of fees.
A zero target changes the conversation, too. A target of 60 days invites a debate about whether 60 is reasonable for your client base. A target of zero points you at specific fee notes: which ones went out with no agreed way of paying, and why that job sat unbilled for five weeks.
How practices move towards it
It usually makes sense to move one client group at a time, starting with recurring compliance work.
- Price recurring work as a monthly fee. Annual accounts, tax returns, bookkeeping and payroll can usually be spread across twelve monthly payments, with a review of the fee each year.
- Agree payment at engagement. The client signs a direct debit mandate when they accept your proposal or engagement letter, so collection is set up before the first fee note.
- Bill extras as they arise. When work goes beyond the agreed scope, say so at the time and bill it promptly, while the client still remembers asking for it.
- Make one-off fees easy to pay. Send a payment link that takes card or pay by bank, with automatic reminders if it isn't paid.
Adfin handles the collection side of that model. Through its integrations with Socket, Engager.app and Sodium, a new client sets up the direct debit as part of accepting your proposal or engagement letter. Monthly fees are then collected by direct debit on the date you set, and the amount can change under the same mandate with advance notice when you review fees. For one-off work, you send a payment link instead, and Adfin's AI Customer Agents follow up over email, SMS or WhatsApp within rules you set. Payments sync back to Xero or QuickBooks against the fee notes they settle.
Where the argument stops
An argument for zero is only convincing if it's honest about its limits.
- Some work can't be scoped up front. Ad hoc advice, investigations and work for a brand-new client with no history are hard to price in advance, so they'll always leave you carrying something.
- Fees taken in advance may need to be returned. If a client leaves part way through the year, your engagement letter should say what happens to fees for work you haven't done. Payment received in advance can also create a VAT tax point earlier than you'd expect, so check the position with your own adviser.
- Not every client will use direct debit. Some won't, and pushing hard may cost you some goodwill. A payment link for the monthly fee, sent on the same date each month and payable by card or pay by bank, is the next best thing.
- Writing work off is a false zero. It clears WIP in the month you lose the fee, so every ratio improves while the practice is worse off. Watch your write-offs alongside your lock-up.
Your professional obligations come first, too, including your professional body's rules on fee disputes and on ceasing to act. A fee dispute is also much easier to settle when your engagement letter set out the terms clearly.
Even with those limits, if you bill most of your recurring work monthly and collect it automatically, the lock-up you're left with tends to come from a short list of one-off jobs that you can review each month.
Common questions
What does a zero debtors practice mean? A practice that collects its fees on an arrangement agreed in advance, usually monthly fees by direct debit, so few fee notes are ever left unpaid.
Can a practice really reach zero WIP? Not literally, while anyone is part way through a job. Billing recurring work monthly in advance gets close, and one-off work still creates some WIP.
Is it acceptable to bill clients in advance? Many practices do, with the terms set out in the engagement letter, including what happens to fees for work not yet done. Check the VAT position with your adviser.
What if a client won't pay by direct debit? Send a payment link for the same fixed fee on the same date each month, payable by card or pay by bank. You lose automatic collection, but reminders can follow automatically if it isn't paid.
How do monthly fees work for annual accounts? You agree a yearly fee and spread it across twelve monthly payments, usually reviewed once a year. With direct debit, the amount can change under the same mandate with advance notice.
Does zero WIP just mean writing work off? It shouldn't. Writing off unbilled time lowers WIP but loses the fee, so track write-offs alongside lock-up.
Sources
- NatWest - The accountancy trends shaping 2024 (accurate as of October 2026) https://www.natwest.com/business/insights/sector-trends/professional-and-business-services/the-accountancy-trends-shaping-2024.html
- ATT - Engagement letters guidance (accurate as of October 2026) https://www.att.org.uk/engagement-letters
- CIOT - Professional Rules and Practice Guidelines (accurate as of October 2026) https://www.tax.org.uk/professional-rules-and-practice-guidelines
- HMRC - VAT guide (VAT Notice 700) (accurate as of October 2026) https://www.gov.uk/guidance/vat-guide-notice-700
- Adfin - Integrations: Socket (accurate as of October 2026) https://www.adfin.com/integrations/socket
- Adfin - Direct debit payments (accurate as of October 2026) https://www.adfin.com/direct-debit-payments
