Big Law firms are sitting on a 17% surge in uncollected AI and tech deal fees as clients delay payment, straining revenue recognition across the market
A survey by analysts at Wells Fargo Legal Specialty Group reveals that the largest law firms ended the first quarter of 2026 with uncollected legal fees — known in the industry as lock-up (the combined total of unbilled time and billed-but-unpaid invoices) — growing by nearly 17% compared to the same period last year. That rise outpaces a more than 13% increase in gross revenue over the same period, meaning firms are generating more work than they are converting to cash. The primary driver is a backlog of fees from AI, data warehouse, and infrastructure transactions — high-value, complex deals that take longer to bill and collect than routine mandates. Clients in these sectors, typically large technology companies and AI-focused businesses, are slower to pay as deal processes extend and internal approval chains lengthen. The dynamic creates a structural cash-flow tension for law firms: revenue is growing, but working capital pressure builds when lock-up rises faster than collections. For partners and practice group leaders, the priority is accelerating billing and collections processes on AI-adjacent mandates while managing the pipeline of transactions that have not yet generated invoices.
Why this matters
Rising lock-up at Big Law firms is not merely a finance operations issue — it reflects the structural complexity of AI and infrastructure transactions, which generate large but slow-to-collect fee streams. When uncollected fees grow faster than revenue, firms face working capital pressure that can constrain lateral hiring budgets, partner distributions, and investment in technology. For clients — particularly the AI and data infrastructure companies at the centre of this trend — it signals that law firms may begin imposing tighter billing discipline, including more frequent interim billing milestones in engagement letters. The trend also illustrates why firms are investing in AI billing and matter management tools: faster invoice generation on complex matters can directly improve cash conversion.
On the Ground
While lock-up management is primarily a finance function, trainees on major tech transactions contribute by ensuring utilisation request and billing milestone documentation is complete and that matter management records are up to date, enabling finance teams to issue invoices promptly. On structured finance or leveraged finance mandates, a trainee would also track CP (conditions precedent) satisfaction dates, which are often the trigger points for billing.
Interview prep
Soundbite
AI deal complexity is creating a cash-flow gap at Big Law — revenue grows, but collections lag behind by a widening margin.
Question you might get
“How does rising lock-up at a law firm affect its ability to invest in lateral hires and technology, and what mechanisms can firms use to address it in their client engagement terms?”
Full answer
Wells Fargo's Legal Specialty Group survey shows Big Law uncollected fees grew nearly 17% year-on-year in Q1 2026, outstripping a 13% revenue rise, with AI and infrastructure transactions identified as the primary driver of the backlog. This matters commercially because lock-up growth erodes the cash conversion that underpins partner distributions and firm investment — a firm with rising revenue but slow collections is financially more stretched than its headline numbers suggest. The wider picture is that AI and data infrastructure deals are structurally more complex and slower-moving than traditional M&A, meaning the billing cycle is longer. This suggests firms will respond by embedding tighter interim billing provisions in retainer and engagement letters for technology mandates going forward.
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