Antidote Lands $5M Seed Round to Streamline Billing Compliance

Law firm billing compliance costs AmLaw 200 firms $7 billion annually in write-offs and rejected invoices. Antidote just raised $5 million to fix it.

Lakestar led the seed round for the London startup, with participation from Concept Ventures, The LegalTech Fund, and industry angels. The funding brings total capital to $7 million following a $2 million pre-seed in 2025. The company will use the funding to accelerate product development and fuel US expansion, building on strong adoption by leading firms across the United States, United Kingdom, and Australia.

“We built Antidote to remove billing friction by automating compliance for law firms, removing the manual work and shifting compliance upstream, when the work is done, not when you’re trying to send out the bill,” said Nicholas d’Adhemar, CEO and co-founder. “This funding validates our vision and enables us to scale our impact across the global legal market.”

D’Adhemar and co-founder Matt Lyons, the company’s CTO, previously built and sold Apperio to PERSUIT in May 2025. At Apperio, they created a spend-management platform for corporate legal departments, giving them deep insight into both sides of the law firm billing relationship.

The platform tackles a billion-dollar problem. Outside counsel guideline violations cause 8-12% of billable hours to be written off or rejected annually. With AmLaw 200 firms generating roughly $140 billion in revenue in 2024, even a 5% loss to billing compliance issues represents $7 billion in annual revenue leakage across the industry.

Traditional approaches rely on manual, end-of-month review processes. By the time compliance issues surface, the work is complete and time entries are finalized. Firms face an impossible choice: write off non-compliant time or risk damaging client relationships by submitting bills that violate their guidelines.

Antidote shifts compliance upstream, catching problems when time entries are created rather than when bills are being finalized. The AI-powered platform integrates seamlessly with existing time-recording and practice management systems, automatically reading every time entry and checking it against both client guidelines and internal firm standards. When it identifies a potential violation, it flags the entry and provides intelligent, autocorrected suggestions in real time.

The technology leverages advanced AI to automatically extract rules from client guidelines, documents that often run hundreds of pages and cover everything from prohibited billing practices to specific task code requirements, rate caps, and staffing restrictions. Unlike legacy solutions that require extensive manual configuration, Antidote ingests these documents and immediately identifies relevant compliance requirements.

The platform meets lawyers where they work. Lawyers can receive compliance feedback via email without logging into yet another system. Each Monday morning, they receive a digest flagging any non-compliant time entries from the previous week and can accept AI-generated, compliant rewrites with a single click.

“What differentiates Antidote is that we were built from the ground up to leverage large language models,” d’Adhemar explained. “We don’t just match rules. We combine document-based guidelines with historical payment patterns to understand what clients actually pay for in practice, creating a nuanced, intelligent compliance engine.”

When a lawyer bills for research on a matter where the client’s guidelines prohibit billing for legal research, Antidote provides specific, actionable guidance. Rather than simply flagging non-compliance, it suggests alternative language and approaches that accomplish the same substantive documentation while adhering to client requirements.

“Nicholas brings rare credibility here,” said Navid Meyer, venture partner at Lakestar. “He’s lived the problem as both a lawyer and a private equity client and has already built and scaled legaltech startups into category-defining platforms for legal spend management. We’re excited to partner with the team as they transform how law firms approach billing compliance.”

The company’s early results demonstrate strong product-market fit. Firms using Antidote have seen measurable improvements in billing efficiency and client satisfaction. For a typical 100-partner firm billing $200 million annually, non-compliant time entries that get written off represent millions in lost revenue. Add the $17 million tied up in working capital from slower collections and the 8-10 partner hours spent monthly on compliance at $800 per hour, and the cost of manual compliance becomes staggering.

Antidote’s real-time approach delivers immediate value. Fewer rejections mean invoices go out faster and get paid sooner. One-click AI fixes free partners to focus on client work rather than billing administration. Most importantly, consistently compliant bills strengthen client relationships and build trust in the billing process.

The company will use the seed funding to expand its engineering team, enhance its AI capabilities, and accelerate US market penetration. With early traction across three continents and growing demand from AmLaw 200 firms, Antidote is positioned to become the standard for automated billing compliance in the legal industry.

“The legal market is ready for this,” d’Adhemar said. “As client pressure on billing practices intensifies, firms need proactive solutions that prevent problems rather than just identifying them after the fact. That’s exactly what we’ve built.”

The company plans to announce several major law firm partnerships in the coming months as it scales its platform to serve the global legal market.