Reducing Lock-Up in Professional Firms: How to Measure It and Bring It Down

What lock-up is and why it matters

Lock-up describes the cash a professional firm has earned but not yet received. It has two parts: work in progress, the value of chargeable time and work recorded but not yet billed, and debtors, bills issued but not yet paid. The term is most familiar in law firms, but the same dynamic applies to accountancy practices, architects, engineering and design consultancies, surveyors and management consultancies: any firm that does the work first and bills afterwards.

Lock-up matters because it is the single biggest driver of working capital in most professional firms. Two firms with the same turnover and profit can have very different cash positions purely because one bills and collects faster. High lock-up means more borrowing, more pressure at quarter ends and tax dates, and less room to invest or distribute profit. It also carries risk: the older WIP and debts become, the less likely they are to be recovered in full.

Reducing lock-up is often the cheapest source of cash available to a firm. Every day taken out of the cycle releases money that would otherwise need to be funded.

How to measure lock-up

Lock-up is usually expressed in days, which makes it comparable over time and between firms of different sizes. It is calculated in two parts and then added together.

• WIP days: take the value of unbilled work in progress at a given date, divide it by the firm’s annual fee income, and multiply by the number of days in the year. This shows roughly how many days of work sit unbilled.
• Debtor days: take the value of unpaid bills at the same date, divide by annual fee income (on a consistent basis for VAT), and multiply by the number of days in the year. This shows roughly how many days of billing are waiting to be paid.
• Total lock-up days: WIP days plus debtor days.

A few points make the measure more useful. Value WIP consistently, ideally at the amount you realistically expect to bill rather than at full standard rates. Treat VAT consistently between debtors and income. Track the figure monthly, not just at the year end, because seasonal patterns can hide the underlying trend. And break it down by team, partner, work type or client, because a firm-wide average often conceals a small number of matters or relationships that account for much of the problem.

Firm size, work type and client base all affect what a sensible lock-up figure looks like, so compare your firm primarily with its own history and with realistic targets set internally, rather than with generic benchmarks.

What drives lock-up

• Billing frequency. Firms that bill only at the end of a matter or project accumulate WIP for the whole of its life.
• Engagement terms. Vague or absent terms about when bills will be issued and when payment is due invite delay.
• Fee earner behaviour. Reluctance to bill, time recorded late, or bills held back while a matter is "nearly finished".
• Write-offs and disputes. Unclear scope or estimates lead to queries, which delay payment and often reduce the bill.
• Disbursements. Third-party costs paid by the firm and recovered only on the final bill.
• Client mix. Large corporate or public sector clients may have long payment processes; individuals may pay slowly without a clear prompt.
• Work type. Contentious legal work on conditional fees, long architectural projects and year-end compliance cycles all create structural lock-up.
• Credit control. No named owner, no chasing routine, and no escalation process.

Most firms have a mix of structural lock-up, which comes with the work they do, and behavioural lock-up, which comes from how they bill and collect. The second is where the quickest gains are.

Billing cadence and engagement terms

The most effective single change for many firms is to bill more often. Monthly or stage-based interim billing on longer matters and projects stops WIP building up, gives clients smaller and more predictable bills, and surfaces disagreements about scope early, while they are easier to resolve.

Engagement terms should support this. Clear terms set out what will be billed and when, how disbursements will be charged, when payment is due and what happens if it is late. Architects and consultancies can align billing with project stages; accountants can agree fixed monthly fees for recurring compliance work; law firms can agree interim billing points and payments on account. Where no payment date is agreed with a business client, GOV.UK explains that the law treats payment as late 30 days after the customer receives the invoice or the service is provided, whichever is later, and that businesses can claim interest and debt recovery costs on late commercial payments. Setting your own terms clearly is usually better than relying on that default.

GOV.UK’s guidance on invoicing and taking payment from customers covers what an invoice should include. Complete, accurate bills with a clear due date and payment instructions are paid faster.

Payments on account and disbursement billing

Asking for money in advance is common practice in many professions and reduces both lock-up and credit risk. A payment on account at the start of a matter or project, topped up at agreed points, means the firm is not financing the client’s work from its own resources.

Law firms should note that money received on account of costs not yet billed is generally client money and must be handled in line with the SRA Accounts Rules, which require client money to be kept separate from the firm’s own money. It can be transferred to the firm’s business account once a bill or other written notification of costs has been given, in accordance with the rules. Your COFA or reporting accountant can advise on the detail.

Disbursements deserve separate attention. Where the firm pays third-party costs such as expert reports, searches, surveys or specialist consultants, billing them promptly, or asking for funds before incurring them, prevents them from sitting in lock-up until the final bill. Where the nature of the work makes that impractical, dedicated disbursement funding can take the cost off the firm’s balance sheet.

Credit control that works

Good credit control is routine, polite and persistent. It works best when there is a clear process and a named person responsible for it, rather than leaving each partner or director to chase their own clients.

• Send bills promptly, to the right person, with a clear due date.
• Follow up before the due date on larger bills to confirm there are no queries.
• Chase on a fixed schedule once a bill is overdue, escalating from reminder to call to partner involvement.
• Offer easy payment methods, including card and direct debit for recurring fees.
• Review aged debt monthly at management level, with actions agreed for each significant item.
• Decide early whether to stop further work for persistently late payers.
• Write off genuinely irrecoverable amounts promptly so reports reflect reality.

Fee earners should see their own lock-up figures. Making WIP and debtor days part of regular performance discussions tends to change behaviour faster than any central policy.

Building a lock-up reduction plan

Lock-up improves fastest when it is treated as a firm-wide project with clear owners, rather than a general aspiration. A practical plan usually follows a simple sequence.

1. Establish the baseline. Calculate current WIP days and debtor days, firm-wide and by team, partner and work type, and identify the largest individual matters and clients.
2. Clean the ledger. Review old WIP and debts, bill what can be billed, and write down what will not be recovered so that the figures are honest.
3. Fix the terms. Update engagement letters and project terms to set out billing points, payment on account and payment dates.
4. Set the rhythm. Agree a billing calendar, a credit control routine and a monthly management review.
5. Make it visible. Share lock-up figures with fee earners and include them in performance discussions.
6. Review and adjust. Track the trend monthly and revisit targets once the quick gains have been made.

Improvements rarely happen evenly. The first round of billing old WIP often produces a visible release of cash, followed by a slower phase where behaviour changes take hold. Planning for that pattern, and deciding in advance how any released cash will be used, whether to reduce borrowing, build reserves or fund growth, helps keep the momentum going. It also gives lenders a clear story when the firm next seeks finance.

Where finance bridges, and where it does not

Finance has an important role in managing lock-up, but it is worth being clear about what it can and cannot do.

Finance bridges lock-up when the underlying work is sound and the delay is a matter of timing. Examples include funding disbursements on contentious cases, releasing cash from issued bills through invoice finance, covering a seasonal peak before year-end billing, or providing working capital while a firm grows. Law firms may use WIP finance against a portfolio of matters, and any firm can use an overdraft, revolving facility or term loan to fund a permanent level of working capital. Our guide to WIP finance for law firms covers the options in detail.

Finance does not fix lock-up caused by infrequent billing, poor engagement terms, weak credit control or work that will never be recovered. Borrowing against those problems simply adds cost. It can, however, buy time while operational changes take effect. A firm that puts a facility in place and simultaneously introduces interim billing and a credit control routine will often find it needs less of the facility over time.

Lenders look at lock-up closely. A firm that can show falling lock-up and a clear plan to manage it is generally better placed to secure lock-up finance on sensible terms, subject to status, lender criteria and approval. Where a sole trader or small partnership borrows, finance of £25,000 or less can be regulated consumer credit, and we will say at the outset if that applies.

Planning for annual pressure points

Lock-up rarely causes a crisis on its own. It usually combines with a large payment falling due: a tax bill, a VAT quarter, a PII renewal or partner drawings. A rolling cash flow forecast that sets expected collections against these commitments helps identify pinch points months in advance, when there are more options. Our guide to funding corporation tax and VAT covers the tax side, and practising certificate fees can be spread through practising certificate finance.

How we can help

We are a whole-of-market commercial finance broker with access to 300+ lenders, including invoice finance providers, specialist professions lenders and high-street and challenger banks. We look at your lock-up, billing pattern and commitments, help you identify whether you need a bridge or a longer-term facility, and approach suitable lenders with a clear case.

See how it works, read about managing cash flow and our work with law firms, accountants and architects, or make an enquiry.

Common questions

This guide is for general information only and should not be treated as legal, tax, accounting or financial advice. Funding availability and lender requirements depend on individual circumstances.