MTC: How Should Lawyers Bill for AI? Time, Tokens, Overhead, and Flat Fees Under ABA Formal Opinion 512 ⚖️🤖
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Matter-specific AI costs: bill actual, metered expenses transparently.
Every lawyer using AI eventually faces the same question at invoice time. 🧾 The draft took eight minutes instead of three hours. The research platform charged a premium for its AI tier. The e-discovery vendor billed by the token. So what goes on the client's bill?
The good news is that the ethics rules already answer most of this. They simply ask us to think more carefully. ABA Formal Opinion 512, issued July 29, 2024, applies Model Rule 1.5 directly to generative AI. There is no AI exception. Your fees and expenses must be reasonable. You must also explain how you charge before or within a reasonable time after the representation begins. 📜
Let's walk through several billing option lawyers are considering and see which ones hold up.
Option 1: Billing the AI's "Time" as Your Time ❌
This one is the easiest to reject. AI does not have billable hours. You do. Opinion 512 is blunt: lawyers who bill hourly "must bill for their actual time." If you spend 15 minutes crafting a prompt and 45 minutes reviewing the output, you bill one hour. You do not bill the three hours the task "used to take."
Billing phantom hours is not a gray area. It violates Rule 1.5(a). It may also implicate Rule 8.4(c), which prohibits dishonesty, fraud, deceit, or misrepresentation. 🚫 Watch your AI-powered timekeeping tools, too. Auto-generated time entries are suggestions. Verify them before they reach the client.
Remember the flip side. Your verification time is real legal work. Checking citations, testing the analysis against the record, and editing for judgment are all billable. Under Rules 1.1 and 3.3, that review is not optional anyway. I made this point in MTC: Even Though AI Hallucinations Are Down: Lawyers STILL MUST Verify AI, Guard PII, and Follow ABA Ethics Rules. ✅
Option 2: Absorbing AI Costs as Overhead 🏢
AI legal review: verify citations and bill actual lawyer time.
For most solo and small-firm lawyers, this is the default answer. Opinion 512 treats tools that function like "equipping and maintaining a legal practice" as overhead. Think of Microsoft 365 Copilot, the AI features inside your practice-management software, or a general-purpose ChatGPT or Claude subscription. You would not bill a client for your word processor. You should not bill them for its AI assistant either, absent advance disclosure and agreement.
Many of these features arrive quietly through software updates. I explored that problem in TSL Labs! MTC: The Hidden AI Crisis in Legal Practice: Why Lawyers Must Unmask Embedded Intelligence Before It's Too Late! If you did not know the AI was running, you cannot justify charging for it. 🕵️
Option 3: Passing Through Access Fees and Token Costs 🔢
AI subscriptions are overhead, not charges passed to clients.
Here the analysis shifts. Opinion 512 offers a helpful example. A lawyer uses a third-party AI service to review thousands of contracts for one client. The vendor charges per use. Billing the client for that actual out-of-pocket cost is ordinarily reasonable.
The key words are matter-specific, metered, and actual. If you need a refresher on how tokens drive AI pricing, see my Word of the Week: What Is a "Token" in AI Parlance? Token usage can be tracked to a specific matter. That makes it look more like a deposition transcript than office rent. 📊
Three guardrails apply:
Bill the actual cost. Do not add a surcharge without clear advance disclosure.
Pass along discounts. If the vendor gives you a volume rate, the client gets it too.
Do not double-dip. If a subscription is already overhead, you cannot also charge per-matter "AI fees" for the same tool.
What about proprietary or in-house AI tools? Absent an agreement, Opinion 512 permits the direct cost plus a reasonable allocation of expenses directly tied to providing the tool. Appropriate disclosure is still required.
Option 4: Flat Fees and Value-Based Pricing 💡
AI competence and disclosure: protect confidentiality, earn client trust.
Flat fees reward efficiency. That is why many observers see AI as the push the billable hour has long needed. My TSL.P Labs episode, Why 96% AI Accuracy Still Fails Lawyers: Ethics, Hallucinations, and the Future of the Billable Hour, explores this tension. So does my shout-out, AI Revolution Challenges Legal Billing: Steve Embry Exposes Shadow AI Use Crisis in Law Firms.
But flat fees are not a loophole. Opinion 512 warns that charging the same flat fee may be unreasonable if AI lets you finish much faster. In its words, "A fee charged for which little or no work was performed is an unreasonable fee." The Rule 1.5(a) factors still govern. They include the skill required, the novelty of the issues, your experience, the results obtained, and the customary fee in your market.
The ethical approach is to price the value of your judgment. A will, a demand letter, or a VA supplemental claim has value because of your expertise. Its value does not come from the minutes on the clock. Set the price on that basis. Then reassess when AI materially changes your workload. Some commentators, writing in ABA Law Practice Today, argue that Opinion 512 applies Rule 1.5 too rigidly. They may be right. Until the guidance evolves, reasonableness remains the test. ⚖️
What You Cannot Bill: Your Learning Curve 🎓
Learning AI is part of your Rule 1.1 duty of technological competence under Comment 8. It is not client work. Opinion 512 says you generally cannot bill for it. The narrow exception applies when a client specifically asks you to use a particular tool. Then you may charge for learning that tool.
Disclosure Ties It All Together 🤝
Rule 1.5(b) requires you to communicate the basis of your fees and expenses, preferably in writing. Rule 1.4 requires reasonable consultation about the means you use. Rule 1.6 may require informed consent before you enter confidential information into certain tools, especially self-learning ones. Rules 5.1 and 5.3 require partners and supervisors to set firm-wide AI billing policies and train staff on them. 🔐
Practically, add a short AI paragraph to your engagement letter. Identify which tools are overhead. Identify which matter-specific AI costs, if any, will pass through at cost. Confirm that hourly entries reflect actual lawyer time only. Sample language might read: "The firm uses AI tools as part of its general overhead at no added charge. If your matter requires a specialized, usage-based AI service, we will tell you in advance and bill only its actual cost." ✍️ Clients appreciate that candor. It also protects you in a fee dispute.
My Two Cents: A Simple Framework ✅
Value-based AI billing: charge for legal judgment, not saved hours.
Here is how I apply all of this:
General AI tools → Overhead. Absorb them. 🏢
Matter-specific, metered AI services → Pass through at actual cost, disclosed in writing. 🔢
Your prompting and review time → Bill it accurately if you bill hourly. ⏱️
Time the AI saved → Belongs to the client under hourly billing. 🤝
Repeatable, AI-enhanced tasks → Consider a reasonable, value-based flat fee. 💡
Your learning curve → Your investment, not the client's. 🎓
Put your AI costs terms in your engagement letters → The last thing you need is a fee/cost dispute with your clients! 😤
AI changes how fast we work. It does not change who we work for. 💼 Price your judgment. Disclose your costs. Never bill a machine's minutes as your own.
MTC
Happy Lawyering!
