Key Takeaways
- Lockup is the combined delay between doing billable work, invoicing it, and actually collecting payment, measured in WIP days plus debtor days.
- Many firms carry well over 100 days of lockup, meaning cash from finished work sits unavailable for months.
- Delayed time entry and inconsistent invoicing cycles are the two biggest drivers of high lockup.
- Real-time timekeeping and disciplined billing cycles can cut lockup significantly without raising rates or cutting costs.
Time Miner helps firms capture time as work happens, closing the gap between doing the work and getting paid for it.
Law firms often measure success by hours billed, not cash collected. That gap is exactly where lockup hides.
Lockup is the silent drag on a firm's cash position. Work gets done, clients get served, and yet the revenue stays trapped somewhere between an unbilled file and an unpaid invoice.
Firms that don't actively track lockup often discover the problem only when payroll or overhead creates a cash crunch. By then, the fix is reactive instead of strategic.
This article breaks down what lockup actually is, why it builds up, and what firms can do to convert finished work into cash faster.
What Is Law Firm Lockup?
Lockup is the total time between performing billable work and receiving payment for it. It combines two separate delays into one number: work in progress (WIP) days and debtor days.
Both stages represent cash the firm has effectively earned but hasn't yet touched. The longer that cash sits locked away, the less working capital a firm has to run its business.
WIP Days vs. Debtor Days
WIP days measure the time between finishing work and actually sending the invoice. This delay usually comes down to slow time entry, unbilled narratives, or invoices sitting in review.
Debtor days measure the time between sending that invoice and the client actually paying it. This stage depends more on payment terms, collections follow-up, and client relationships.
Together, these two numbers form total lockup. A firm can have excellent collections but still carry high lockup if its WIP side is slow, and vice versa.
How to Calculate Lockup
Why Lockup Builds Up
Lockup rarely comes from one single failure. It's usually the result of several small delays compounding across a firm's billing cycle.
Delayed Time Entry
Attorneys reconstructing billable hours days or weeks after the work was done tend to underreport time, miss entries entirely, or write vague descriptions that slow invoice approval.
This delay alone can add weeks to WIP days before a single invoice ever reaches a client's inbox.
Inconsistent Invoicing Cycles
Firms without a fixed billing cadence often let invoices pile up until someone finds time to review and send them. Without a set rhythm, WIP simply keeps aging.
Slow Client Payment Terms
Even well-run billing cycles can stall out if client payment terms are too generous or collections follow-up is inconsistent. Debtor days climb quietly until someone finally checks the aging report.
The Real Cost of High Lockup
High lockup isn't just an accounting inconvenience. It has direct, compounding effects across the firm.
Cash Flow Strain
Payroll, rent, and overhead don't wait for lockup to clear. Firms with high lockup often end up financing operations out of reserves or credit rather than actual collected revenue.
Even a firm with strong annual fee revenue can feel this strain. Trimming lockup by even a few weeks can release a meaningful amount of cash without adding a single new client.
Increased Write-Offs
The longer WIP ages, the higher the risk it gets discounted or written off entirely. Stale time entries are harder to justify to clients and easier for partners to quietly discount.
A Hidden Driver of Attorney Burnout
Chasing down old file notes to reconstruct time, combined with pressure to close out aging WIP at month-end, adds administrative strain on top of casework. Over time, this kind of reactive billing pressure contributes to Attorney Burnout in ways that rarely get connected back to the root cause.
High-Lockup Firms vs. Low-Lockup Firms
How to Reduce Lockup
Capture Time in Real Time
The single biggest lever for reducing WIP days is capturing time as it happens rather than reconstructing it later. Modern Timekeeping Software can log time automatically from calls, emails, and document activity instead of relying on memory.
Time Miner was built around this exact problem, helping firms capture billable time contemporaneously so WIP doesn't sit unbilled for weeks at a time. That immediacy alone can meaningfully shrink lockup.
Set Firm-Wide Billing Strategies
Consistency matters more than perfection. Firms that commit to fixed invoicing cycles, standardized time-entry deadlines, and clear escalation for stale WIP see measurably lower lockup than firms that leave billing to individual discretion.
Codifying these habits into firm-wide Billing Strategies, rather than leaving them to each attorney, keeps lockup from creeping back up once it's under control.
Consider Alternative Fee Structures
For some practice areas, shifting part of the portfolio toward Value Billing, where fees are tied to outcomes rather than strict hours, can reduce the invoicing delays that come with complex hourly narratives.
This isn't a fit for every matter, but it can shorten the WIP stage for well-scoped, predictable work.
Track Aging WIP by Timekeeper
Many finance teams maintain an internal attorney billing chart that shows WIP age by timekeeper and matter, making it easy to spot where delays are concentrated before they become a cash flow problem.
This kind of visibility turns lockup from an abstract firm-wide number into something actionable at the individual level.
Final Thoughts
Lockup doesn't announce itself the way a missed deadline does. It builds quietly, one delayed time entry and one late invoice at a time, until it shows up as a cash flow problem months later.
Firms that treat billing speed as a core operational metric, not an afterthought, consistently carry less lockup and more usable cash. The tools and habits to fix it already exist; the work is in applying them consistently.
Frequently Asked Questions
Q.1 What is a good lockup number for a law firm?
A: There's no universal target, but firms with disciplined billing practices often keep total lockup well below 100 days, while poorly managed firms can exceed 130 to 150 days.
Q.2 Is lockup the same as accounts receivable?
A: No. Lockup includes both unbilled work in progress (WIP) and outstanding debtors, while accounts receivable only covers invoices that have already been sent.
Q.3 How often should firms review lockup?
A: Monthly reviews are common practice, though firms with cash flow pressure often benefit from checking aging WIP and debtor reports weekly.