Mercury vs Relay for a Law Firm's Operating Account

A solo practice or small partnership with one operating entity has straightforward needs: payroll, rent, a tax reserve, and enough working capital to cover the gap between doing the work and collecting on invoices. Relay's free sub-accounts handle that split cleanly without any monthly cost. A larger firm running multiple practice groups as informal profit centers, or a firm with a separate entity for a title company or other ancillary service, gets more value from Mercury's multi-account and multi-entity structure, plus the ability to pull balances into an internal reporting system if the firm has any technical staff who'd build that.

Match the firm's structure to an operating account setup:

• A solo practice or small partnership with one operating entity fits Relay's free sub-accounts for payroll, rent, a tax reserve and working capital.
• A larger firm running practice groups as informal profit centers gets more from Mercury's multi-account structure.
• A firm with a separate entity, such as a title company or other ancillary service, benefits from Mercury's multi-entity setup.
• A firm with technical staff who could build internal reporting can pull balances through Mercury's API.

Law firms often bill monthly but collect slower than that, especially on matters where a client is disputing fees or waiting on their own cash. A dedicated working capital sub-account, funded by a fixed percentage of collections and sized against your typical collection lag, keeps a slow-paying client from putting pressure on payroll. This is a pure account-structure fix and works identically on either platform; the only difference is how fast you can stand it up, and Relay's instant, free sub-accounts win that specific race.

A firm carrying a healthy operating reserve, beyond the working capital line above, is holding cash that could be earning yield instead of sitting flat. The effective federal funds rate is currently 3.63%¹, and Mercury's automated Treasury sweep captures yield near that level on operating cash above your buffer without a partner having to remember to move it. This applies only to the firm's own operating reserve, never to client trust funds, which are governed by separate IOLTA rules on where interest goes and typically can't be swept into a general Treasury product regardless of which bank holds the trust account.

A firm bridging a slow collections quarter with a line of credit is borrowing at a cost tied to the bank prime rate, currently 6.75%², a meaningfully higher cost of carrying debt than it was a few years back. Before drawing on a line to cover a payroll gap, check whether the real issue is a genuinely slow quarter or a collections process that's let receivables run longer than they should; a credit line used to paper over weak collections discipline is an expensive way to avoid fixing the underlying process.

That distinction matters because the fix is completely different depending on which one it is. A genuinely slow quarter, a large matter that settled later than expected, a client industry going through a rough stretch, is a timing problem a working capital reserve and, if needed, a short credit draw can smooth over without changing anything structural. A collections process that consistently lets invoices sit sixty or ninety days before anyone follows up is a process problem, and financing around it every quarter just makes an underpriced, underenforced billing practice more expensive to sustain rather than fixing what's actually wrong.

Most small and mid-sized firms rely on an outside accountant or bookkeeper rather than in-house finance staff, which makes role-based account access a real, practical feature rather than a nice-to-have. Relay's native QuickBooks Online and Xero integrations, paired with limited access for that outside accountant, keep the operating books current without anyone sharing full login credentials. Mercury supports similar access controls and adds a documented API for a firm with any internal technical staff who want to pull operating data into their own reporting rather than relying entirely on an accountant's periodic reports.

Confirm your state bar's current trust accounting rules with your own ethics counsel, since this guide covers operating banking only. Decide whether your firm needs one entity or several represented in the account structure. Estimate your typical collection lag so a working capital sub-account is sized correctly from the start rather than guessed at. And ask whoever handles your books, in-house or outside, which platform's integration they already know, since that familiarity often saves more time over a year than any single feature difference between the two banks.