Every law firm carries work in progress. The trouble starts when hours sit unbilled for weeks, because older time is harder to bill, easier to dispute and more likely to be written down.
This guide is a practical plan, not a vendor ranking. It explains how to measure unbilled WIP, where it gets stuck and what to change in the first 30 days. Tools are described by category so you can match them to your bottleneck.
Key Takeaways
- WIP is not receivables: WIP is recorded work not yet invoiced; accounts receivable is invoiced work not yet paid.
- Measure WIP days and aging bands first: 0–30, 31–60, 61–90 and 90+ days.
- Most WIP stalls in four places: late time entry, slow prebill review, unclear ownership and billing-rule rejections.
- A weekly rhythm beats a month-end scramble: a short Friday WIP review with named owners.
- Tools help only after the process is set: capture tools fix late entries; prebill review tools fix rule problems.
What is unbilled WIP at a law firm?
Short answer: unbilled WIP is the value of time and expenses recorded against matters but not yet sent to the client on an invoice.
It sits between the work and the bill. Once invoiced, it moves into accounts receivable. Both tie up cash, so finance teams often track them together as "lockup."
| Stage | What it means | Who usually owns it |
|---|---|---|
| Unrecorded time | Work done but not entered | Timekeeper |
| Unbilled WIP | Entered, not yet invoiced | Billing partner and billing team |
| Accounts receivable | Invoiced, not yet paid | Billing and collections |
| Collected | Cash received | Finance |
Why does unbilled WIP grow?
Short answer: because time is entered late, prebills wait for partner review, nobody owns follow-up, and entries fail client billing guidelines and come back for rework.
- Late time entry: reconstructed time is thinner and harder to defend.
- Prebill latency: drafts sit in a partner's queue.
- No clear owner: billing assumes the partner will act, and the partner assumes billing will.
- Guideline rejections: block billing, vague narratives or wrong rates trigger rework or e-billing rejections.
- Matter setup gaps: missing engagement terms, rates or billing contacts hold invoices back.
- Contingent and milestone matters: some WIP is meant to wait. Separate it so it does not hide real problems.
How do you measure unbilled WIP?
Short answer: track total unbilled WIP, WIP days and an aging report by band, by partner and by client, every week.
WIP days estimates how long work waits before billing. A simple version: divide unbilled WIP by your average daily billings over the last 90 days.
| Metric | How to calculate | Why it matters |
|---|---|---|
| Unbilled WIP | Sum of unbilled time and expenses | Size of the problem |
| WIP days | Unbilled WIP ÷ average daily billings | Speed of conversion |
| Aging bands | WIP split into 0–30, 31–60, 61–90, 90+ days | Shows what is going stale |
| Prebill turnaround | Days from draft prebill to approval | Finds review bottlenecks |
| Time entry lag | Days from work date to entry date | Finds capture problems |
| Write-downs on old WIP | Value written off by aging band | Shows the cost of delay |
Worked example: a firm with $600,000 unbilled WIP and $20,000 average daily billings has 30 WIP days. Cutting that to 20 days would release $200,000 of work into invoices.
The four bottlenecks and how to fix each
1. Capture gap: time is entered late
Fix: set a daily or next-day entry rule, report entry lag by timekeeper and use automatic capture tools for people who reconstruct time.
- Publish a weekly entry-lag report, by person.
- Block month-end reconstruction by closing time periods weekly.
- Give partners their team's lag numbers, not just their own.
2. Prebill latency: drafts wait for review
Fix: set a turnaround target, send smaller prebills more often, and escalate after a fixed number of days.
- Use a two-touch rule: one reminder, then escalation within 48 hours.
- Split large matters into shorter billing cycles.
- Let billing staff approve routine edits within agreed limits.
3. Ownership gap: nobody follows up
Fix: assign one owner per matter for WIP, record the next action and review owners in a weekly meeting.
4. Compliance rework: entries break billing rules
Fix: check entries against client guidelines before the prebill, not after the client rejects the invoice.
Common problems include block billing, vague task descriptions, rate mismatches and missing task codes. Our guide to block billing (https://www.lumay.ai/blogs/what-is-block-billing-examples-risks-ai-review-checks) shows examples and checks.
How to prioritize WIP by value and age
Short answer: work the oldest and largest balances first, because they carry the most write-down risk and release the most cash.
| Value tier | 0–30 days | 31–60 days | 61–90 days | 90+ days |
|---|---|---|---|---|
| Under $5,000 | Normal cycle | Reminder | Partner review | Write-off decision |
| $5,000–$15,000 | Normal cycle | Owner follow-up | Escalate to practice lead | Escalate to managing partner |
| Over $15,000 | Owner check | Escalate | Managing partner review | Weekly executive review |
Set reminder points at 15, 30 and 45 days so items never reach the 60-day band without a decision.
The Friday WIP Review: a 30-Minute Agenda
➤ Review the aging report: total WIP, WIP days and anything newly over 30 days.
➤ Go through the top ten balances by value; confirm owner and next action.
➤ Check prebills waiting more than five business days.
➤ Flag entries blocked by billing-guideline issues.
➤ Confirm matters with setup problems: rates, engagement letters, billing contacts.
➤ Record decisions and owners; carry open items into next week.
The 30-Day Plan
Week 1: Measure
- Pull a WIP aging report by partner, client and practice group.
- Calculate WIP days and time entry lag.
- Separate contingent and milestone matters.
Week 2: Assign and set rules
- Name one WIP owner per matter.
- Publish time entry and prebill turnaround rules.
- Start the Friday review.
Week 3: Clear the backlog
- Work the 90+ and 61–90 bands first.
- Make write-off or bill decisions for stale small balances.
- Fix matter setup gaps holding invoices.
Week 4: Prevent recurrence
- Add pre-submission checks for billing guidelines.
- Decide which tool category, if any, addresses your largest bottleneck.
- Set monthly targets for WIP days and aging.
How do you clean up narratives in old WIP?
Short answer: rewrite vague entries before the prebill, split block-billed time into tasks, and confirm each line against the client's billing guidelines.
- Vague task words: replace "review," "attention to" or "work on file" with the document, purpose and outcome.
- Block billing: split multi-task entries into separate lines with their own time.
- Wrong timekeeper or rate: confirm against the engagement letter before the bill goes out.
- Missing task or activity codes: add them where the client uses e-billing.
- Non-billable items: move them out early so partners are not editing at prebill.
Ask timekeepers to fix their own entries within a set window, so billing staff are not guessing at the work.
Common mistakes when reducing WIP
- Mass write-offs to hit a target: the number improves, but revenue is lost and the cause remains.
- Month-end pushes only: balances drop briefly, then rebuild.
- Buying a tool first: software cannot fix missing ownership or unclear rules.
- Ignoring partner workload: prebills stall where reviewers have too many matters.
- Reporting firm totals only: problems hide unless you split by partner, client and practice.
Which tools help reduce unbilled WIP?
Short answer: time capture tools reduce late entries, prebill review tools catch rule problems early, and billing systems provide aging reports. Pick the category that matches your worst bottleneck.
| Bottleneck | Tool category | Examples named on vendor sites |
|---|---|---|
| Late or thin time entries | AI or passive time capture | Intapp Time, Laurel, Aderant iTimekeep, PointOne, Smokeball AutoTime |
| Rule violations and rework | Pre-bill review and guideline checks | Intapp Time (checks at entry and prebill), PointOne bill review |
| No visibility | Billing and practice management reports | Your billing system's WIP aging report |
| Ownership and follow-up | Workflow routing and task tracking | Billing system workflows or task tools |
This table is not a ranking. Fit depends on your billing system, firm size and which bottleneck costs you most. For a broader view, see our legal billing software comparison (https://www.lumay.ai/blogs/best-legal-billing-software-for-law-firms) and our guide to pre-bill review software (https://www.lumay.ai/blogs/pre-bill-review-software-law-firms).
Questions to ask a vendor
- Which billing systems and versions do you integrate with?
- Do you check entries against client outside counsel guidelines, and when?
- Can you report entry lag and prebill turnaround by timekeeper?
- How are flagged entries routed and to whom?
- What do lawyers have to change in their daily routine?
- What data leaves our environment, and where is it stored?
Our own product: LuMay BillingGuard
Disclosure: LuMay publishes this blog. BillingGuard is our product.
BillingGuard, part of our legal agent suite, looks for setup, approval, rate and evidence issues and routes each one to an owner before submission. It shows revenue exposure and submission readiness. It does not replace your billing system.
Source: https://www.lumay.ai/ai-products/legal-agent/billingguard
For a step-by-step entry audit, see how to audit legal time entries before invoices go out (https://www.lumay.ai/blogs/audit-legal-time-entries-before-invoices-go-out).
Sources
- https://www.leanlaw.co/blog/the-fastest-way-to-conduct-a-firm-wide-review-of-unbilled-time-and-expenses-a-complete-guide-for-mid-sized-law-firms/
- https://www.windyhillpartners.net/services/law-firm-wip-management.html
- https://www.intapp.com/time-tracking/
- https://www.laurel.ai/solutions/legal
- https://www.aderant.com/solutions-itimekeep/
- https://www.getpointone.com/
- https://www.smokeball.com/features/do/autotime
- https://www.lumay.ai/ai-products/legal-agent/billingguard
