How do I collect an unpaid invoice from a law firm client?
How to collect an unpaid law firm invoice
Published May 13, 2026
Short answer
Law firm collections live under two constraints other businesses don't have: client trust accounts (IOLTA) hold retainer funds that can only be transferred against billed hours, and state bar rules govern how firms can communicate with clients about unpaid fees. The honest sequence is to bill clearly, apply trust funds against billed work promptly, and follow up on uncovered balances with respectful written and phone reminders. Never threaten to withdraw from a representation as leverage; that crosses bar ethics lines.
Law firm AR has rules unlike any other professional service. Most state bar associations require firms to hold unearned retainer fees in a separate IOLTA (Interest on Lawyers Trust Account) and transfer funds out only after the work has been billed and the client has had a chance to review. This means the firm typically has the money but must follow a specific process to apply it. If your firm is sloppy on the trust-to-operating transfer, you create your own collection problems by under-applying funds you already hold.
For uncovered balances (work billed beyond the retainer or non-retainer matters), the day-3 follow-up call works just like any other professional service. Confirm the bill arrived, ask if there are questions on any line item, offer a payment plan if hours unexpectedly ran over. Most clients pay readily when they understand the work; disputes usually center on hours billed for specific tasks rather than the engagement overall.
Bar ethics rules constrain the collection script. You cannot threaten to withdraw from active representation as leverage to collect fees on a different matter, and you cannot threaten to file or sit on a court filing based on payment. Withdrawing from representation requires court approval in litigation matters and adequate notice in transactional ones. The collection process needs to keep the legal representation and the billing dispute on separate tracks.
Late fees and interest on legal bills are jurisdiction-specific. Some state bars allow them with prior written notice in the engagement letter; others restrict them. Check your state bar's fee rules before adding any late fee. A 1% per month service charge with proper notice is usually allowed; punitive amounts are not.
Syntharra handles the day-3 first-party call for law firms invoicing through QuickBooks or Xero. The AI identifies on the firm's behalf, confirms the invoice number and balance, and offers a payment link or to take payment over the phone. The script avoids any language that could implicate bar ethics rules around collection or representation.