Ask most law firm finance directors where their biggest pool of untapped cash sits, and they won't point to fee rates or headcount. They'll point to work that has already been done, already been paid for in salaries and overheads, and is still sitting on the books unbilled.
Work in progress is the gap between effort and income. Every day that gap stays open, the firm is lending money to its clients interest-free. Yet in most firms WIP is treated as a finance problem, raised in a monthly report, briefly discussed, then left with the finance team to chase.
That framing is the problem. WIP is created by fee earners, shaped by partners, and only ever measured by finance.
The WIP challenge in law firms
WIP is the value of chargeable work performed but not yet invoiced. Combined with debtor days, it forms lock-up: the total time taken to convert effort into cash. In most firms it's the single largest component of working capital, and it's harder to control in legal practice than almost anywhere else. Matter lifecycles are long and unpredictable, fixed and contingent fee models defer cash, corporate and public sector clients dictate payment terms, and billing feels like a relationship risk.
Rarely does high WIP come down to one broken process. It builds through small, individually reasonable decisions, a time entry left until Friday, a bill held back until the next milestone, a difficult fee conversation postponed. Repeated for a year, those decisions harden into a norm where high WIP is simply how the firm operates.
One blind spot is worth naming: the pull of the big file. Fee earners concentrate on the large, complex matters where billing genuinely does have to wait for completion, while a long tail of smaller matters sits unbilled, individually too minor to prompt action, collectively worth as much as the headline case. That tail is usually where the recoverable cash is hiding.
The cost of unmanaged WIP
The financial cost is easy to quantify, which makes it the most persuasive argument a finance team has.
Take a firm turning over £10 million a year - roughly £27,000 of revenue a day. At 120 days of lock-up, around £3.2 million is tied up in unbilled work and unpaid invoices. At 90 days, that falls to around £2.4 million. The 30-day improvement releases roughly £800,000 of cash the firm has already earned. No fee increases, no cost-cutting, no new clients.
The maths scales both ways. A £3 million firm at 130 days has around £1.1 million tied up; 25 days of improvement frees over £200,000. Above £50 million, a single lock-up day can represent £130,000 or more.
But ageing WIP doesn't just delay cash, it destroys value. The further a client is from the work, the less they remember its worth and the more likely they are to query the bill, so old WIP converts at a discount, if at all. Every write-off is a salary cost the firm already paid. And a matter with runaway WIP is often a matter with a scope problem, a difficult client, or a fee earner who is struggling, the number is the symptom, but nobody looks upstream.
A firm can be highly profitable on paper and still run out of money. Profit is an accounting outcome; cash pays salaries.
How finance teams manage WIP - and why they can't do it alone
Finance teams generally know exactly what needs to happen: WIP and lock-up reporting by fee earner and department, ageing analysis at 30, 60 and 90 days, exception reporting on missing time, KPIs fed into partner reviews, and forecasting built on billing pipelines rather than optimism.
What finance cannot do is any of the things that actually reduce WIP. It cannot record someone else's time, decide whether a matter has reached a billable milestone, judge whether a bill is commercially appropriate, or have the scope conversation when a fixed fee is being overrun. It certainly cannot instruct a partner to bill a client that partner has acted for since 2004.
This is the structural trap: finance owns the measurement but none of the levers. So the report circulates, everyone agrees the numbers are too high, and nothing changes. The reports also carry an implicit accusation, which triggers defensiveness rather than action. Teams that reframe it, from "your WIP is too high" to "here are five matters where the work looks complete, can we bill them?" - get considerably further, because they're offering a decision rather than a criticism.
The role of partners in WIP management
Partners are the pivot point. They set matter-level billing decisions, model behaviour for their teams, and hold the relationships that make or break a billing conversation. In practice that means four things: setting fee expectations at the outset through disciplined engagement letters; billing to a rhythm rather than to completion, since clients budget more easily against regular invoices than a single large one; raising scope and cost escalation with the client at the moment it happens, when the conversation is still easy; and reviewing WIP with their own team monthly, because associates record time promptly when their partner asks about it and won't when they don't.
There's a fairness point too. Junior fee earners are often held to time-recording standards partners themselves don't meet. That inconsistency is noticed, and it quietly undermines every process the firm puts in place.
How firms create a culture of WIP ownership
Culture is where WIP management either sticks or quietly reverts. The firms that make it stick tend to do five things:
- Make the numbers visible. Transparency of lock-up by fee earner and department changes behaviour more reliably than any policy document.
- Embed billing in the workflow. Bill with the advice, while the value is fresh in the client's mind, not as a separate monthly exercise bolted onto the real work.
- Put it in objectives. If lock-up sits in firm-wide KPIs but not in appraisals or partner remuneration, it's a stated priority rather than a real one.
- Recognise good behaviour, not just poor. Most firms only mention WIP when it's bad, which frames it as a compliance burden rather than a professional standard.
- Challenge the "everyone carries high WIP" belief directly. It's the most durable obstacle, and it needs benchmark data rather than exhortation.
How tech is improving WIP management
Technology won't fix a cultural problem, but it removes the friction that gives poor habits cover. Mobile entry, calendar and email integration and passive capture have cut the gap between doing work and recording it from weeks to hours and since inaccurate time distorts every downstream figure, that's foundational. Live dashboards let a partner check their department's position on a Tuesday afternoon rather than waiting for the finance pack, turning WIP from a historical report into an operational metric. Automated prompts for missing time, ageing alerts and scheduled interim billing runs remove the dependency on someone remembering. And e-billing and online payment shorten the debtor half of the cycle.
The caveat matters, though. Most firms already own software capable of all of this. The gap is almost never capability; it's consistent use. A system used at 40% of its potential won't outperform a disciplined culture with a spreadsheet.
What good WIP management means for firms
Firms that get this right describe the benefits in similar terms and only some are financial. Working capital is released without any commercial cost, making it the lowest-risk funding available to a law firm. Borrowing falls and covenant headroom improves. Cash flow becomes predictable, which makes drawings, tax and VAT far less stressful to plan around. Realisation rises, because bills raised close to the work are queried and discounted less.
Client relationships improve, too, which surprises people. Regular, proportionate invoicing is generally what clients prefer. The unexpected six-figure bill after nine months of silence is what damages trust, not the monthly invoice.
None of it is achievable by a finance team alone. It requires fee earners recording time as they work, partners billing to a rhythm and holding fee conversations early, leadership treating lock-up as a strategic metric rather than a monthly irritation, and finance providing the visibility that makes all of it possible.
WIP management isn't a finance function. It's a firm-wide discipline that finance happens to measure.
If you would like to discuss this topic in more detail, reach out to Sam Hyde.
