The difference between WIP aging and WIP turnover, unbilled WIP thresholds, and billing velocity targets — the leading indicators that predict a realization rate problem weeks before it shows up.
WIP & Billing for Accounting Firms
Most firms track one WIP number: how old the oldest unbilled work is. That catches the outliers, but it misses a slower, firm-wide problem — new work entering the pipeline faster than it's billed out. WIP management means watching both the age of individual jobs and the overall velocity of the book.
Target: majority of WIP under 45 days; flag anything over 60.
WIP aging — a work in progress aging report, in the language most practice management systems use — is a leading indicator of billing risk. Firms that let WIP age past 60 days see higher write-down rates, because clients push back harder on invoices for work they don't remember clearly and partner review becomes harder to justify.
WIP turnover (days) = average WIP balance ÷ average daily billings.
WIP turnover tells you something WIP aging doesn't: how many days of billings are sitting in unbilled WIP at any given time, across the whole book. A firm can have acceptable aging on paper while turnover is quietly climbing, because new work keeps entering faster than it's billed — a firm-wide velocity problem an aging report alone won't surface.
Money already earned, not yet invoiced.
Unbilled WIP is work the firm has completed and could invoice today but hasn't. Left unmonitored, it becomes the primary source of both write-downs (as it ages past a client's memory of the engagement) and cash flow strain, since it's earned revenue the firm can't yet collect against.
Target: invoice within 0–14 days of work completion.
Billing velocity — also called billing cycle time — is the number of days from work completion to invoice. It directly affects both cash flow and realization rate: firms that invoice within 0–14 days collect at higher rates and generate fewer disputes, while billing lag beyond 30 days correlates strongly with higher write-down frequency.
Weekly review beats month-end reconciliation.
Effective WIP management is a weekly habit, not a month-end cleanup: review aging movement by partner and service line, flag anything approaching 60 days before it crosses, and reconcile budget vs. actual hours on open engagements so scope creep gets caught before it inflates WIP further.
Push-button visibility replaces manual WIP pulls.
A time and billing dashboard connects directly to the system recording hours and invoices, so WIP aging, WIP turnover, and billing velocity update automatically instead of requiring a manual export before every partner review.
| Metric | Best-in-Class Target | Warning Threshold | Review Cadence |
|---|---|---|---|
| WIP Aging | Majority under 45 days | 60-day bucket growing | Weekly aging movement |
| WIP Turnover | Stable or declining days | Rising trend over 2+ months | Monthly |
| Billing Velocity / Cycle Time | Invoice within 0–14 days | Lag beyond 30 days | Weekly |
| Budget vs. Actual Hours | Within 10% of budget | Over 20% variance | Per engagement |
FirmMetrics™ delivers push-button WIP and job profitability dashboards, updated automatically from CCH Practice or Practice CS — surfacing WIP aging, WIP turnover, and billing velocity without manual report pulls or export cycles, so unbilled work is visible the moment it's ready to invoice.
For the full benchmark set across realization, utilization, WIP, and AR, see our Accounting Firm KPI Benchmarks guide.
Best-performing accounting firms keep the majority of WIP under 45 days and treat the 60-day bucket as an active intervention threshold. This holds at the service-line level too — a healthy firm-wide number can hide one service line's WIP quietly running past threshold.
WIP turnover (in days) = average WIP balance ÷ average daily billings. It measures how many days of billings sit in unbilled WIP across the whole book, while WIP aging measures how old the oldest individual jobs are. A firm can have healthy aging while turnover climbs, because new work is entering faster than it's billed out — the two metrics catch different problems.
Unbilled WIP is work the firm has completed but hasn't yet invoiced — revenue already earned but not yet converted to cash. Left unmonitored, it's the primary driver of both write-downs, since older work gets written down more, and cash flow strain, since the firm can't collect against work it hasn't billed.
Best-performing firms invoice within 0–14 days of work completion. Billing lag beyond 30 days is strongly correlated with higher write-down frequency, since clients push back more on older invoices and the connection to the work performed fades.