How To Accept Payments For A Corporate Attorney

A corporate attorney bills against retainers held in trust, and that single fact governs everything else. Client funds are not firm income until they are earned, the rules for holding and moving them are strict, and the payment setup exists inside that framework. Here is how it should run, from engagement to collection.

Updated July 28, 2026. Figures cited below; reviewed quarterly.

The trust accounting frame comes first

Advance fees and retainers belong to the client until earned, and applicable professional conduct rules govern how they are held, in what account, how they are reconciled, and how earned amounts are transferred to the firm. Those rules also address who bears payment processing costs, since a processing fee deducted from a client trust deposit can create a shortfall that is itself a violation. This is jurisdiction-specific, and it is the one area of this article where reading the actual rules that bind your licence is not optional.

By the numbers (July 28, 2026)

Square prices this lane at 3.3% + 30¢ online or on a card-paid invoice in 2026. A $7,500 retainer replenishment costs $248 to process; by ACH bank transfer (1%, capped at $10) it costs $10.00, a $238 difference. Where the rules permit card replenishment, convenience keeps balances topped up, though at this size bank transfer is the standard corporate route.

How corporate legal money actually arrives

Four flows. Evergreen retainers: an advance balance held in trust, drawn down as work is billed and replenished when it falls below a threshold. Hourly billing against those balances, invoiced monthly with detail. Flat and productised fees for defined matters, entity formation, standard agreements, compliance reviews, which are increasingly common and simpler to collect. And transactional or success-based fees where the engagement permits them. Corporate clients pay from accounts payable, which behaves nothing like a consumer.

Evergreen retainers, which solve collection

A retainer that replenishes automatically when the balance drops below a stated floor removes the firm's collection problem almost entirely, because the money is already there before the work is billed. Set the threshold and the replenishment amount in the engagement letter, agree the payment method at signing, and notify before each replenishment. Firms operating this way spend no time chasing invoices; firms billing monthly in arrears spend a meaningful share of partner time doing exactly that, which is the most expensive collections department imaginable.

Flat fees on defined matters

Corporate clients increasingly prefer knowing the cost, and defined matters suit it: formations, standard agreement drafting, annual compliance work, policy suites. Flat fees can be collected in full at engagement, which is cleaner than trust accounting for that portion where the rules permit treating them as earned on receipt, and clarity here matters because the treatment differs by jurisdiction and by how the fee is characterised. Productising the repeatable work also makes the firm easier to buy from, which matters more to corporate clients than hourly rate comparisons.

Corporate payables and the rails

Corporate clients pay through accounts payable systems that need matter numbers, purchase order references, and invoice detail in a specific format, and an invoice missing those sits unpaid without anyone objecting to it. Ask at onboarding what their process requires. On rails, bank transfer is standard at corporate legal amounts and the fee difference is material, while card acceptance is genuinely useful for smaller flat-fee matters and for retainer replenishments where convenience keeps the balance topped up. Whichever is used, the trust accounting rules govern how the money is handled once it arrives.

Sources

• Swipesum — Square Fees Explained 2026 (verified against Square's published pricing)
• NerdWallet — Square Fees: Calculator and Pricing for 2026

What people ask me

What governs how a law firm holds retainers?

Applicable professional conduct rules covering which account funds sit in, how they are reconciled, and how earned amounts transfer to the firm, including who bears processing costs.

Why do processing fees matter for trust accounts?

Because a fee deducted from a client trust deposit can create a shortfall that is itself a rules violation, which is why the treatment must be checked rather than assumed.

What is an evergreen retainer?

An advance balance held in trust that replenishes automatically when it drops below a stated floor, so the money is there before the work is billed.

Why do flat fees suit corporate work?

Clients prefer knowing the cost, and defined matters like formations and compliance reviews productise cleanly, which makes the firm easier to buy from.

What do corporate clients need on an invoice?

Matter numbers, purchase order references, and their required format. An invoice missing those sits unpaid without anyone objecting to it.

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