Can Lawyers Bill for AI Work? The Billing-Ethics Rules Every Firm Hits in Month One

Yes, lawyers can bill for AI-assisted work, but only for the time they actually spend, not the hours the AI saved. Under ABA Formal Opinion 512 and Model Rule 1.5, an hourly bill has to reflect real time worked. If a research memo that used to take five hours now takes ninety minutes plus your review, you bill ninety minutes plus review. You cannot charge the client the pre-AI total for post-AI speed.

That is the whole billing-ethics problem in one sentence, and almost every firm runs into it in the first month of using AI. The tool works. A task collapses from an afternoon to a coffee break. And then the invoice asks a question the marketing never did: what do you actually charge for the two hours you no longer spent?

This post answers that question with the rules that govern it, then the part the rules do not resolve — how to price your work when AI keeps compressing your hours. The numbers below are illustrative examples, not survey data; your rates and results will differ.

The short version: bill your time, not your leverage

ABA Formal Opinion 512, issued July 29, 2024, is the first comprehensive ABA guidance on lawyers using generative AI, and it devotes a full section to fees. The governing principle is old and simple: Model Rule 1.5 requires that a lawyer's fee be reasonable, and the rule lists the factors that make it so, starting with "the time and labor required."

Opinion 512 applies that rule to AI in three moves that matter for a small firm.

Bill actual time. When you charge hourly, you bill the time you actually spend. The opinion's own example: a lawyer who uses AI to draft a pleading in fifteen minutes may bill that fifteen minutes plus whatever time it takes to review and correct the draft, and no more. The speed belongs to the client, not to your timesheet.

Do not bill clients to learn the tool. A lawyer "may not charge clients for time necessitated by their own inexperience." Learning a generative AI tool you plan to use across your practice is your investment, the same as learning a new research platform. Opinion 512 carves out one narrow exception: if a particular client asks you to use a specific tool you do not know, the time to get up to speed on that tool for that matter may be billable.

Charge for the tool only by the rules for expenses. A general AI subscription you run across every matter is overhead, like your office lease or your Wi-Fi, and Opinion 512 says you treat it as overhead unless you disclose otherwise to the client in advance. A per-use charge from a third-party AI service, incurred for one client's matter, can be passed through as an out-of-pocket expense at actual cost with no markup. Either way, if you are going to bill for the tool, you have to explain the basis for the charge, preferably in writing.

Opinion 512 is national guidance, not a binding rule in your state, but it is the analytical spine that state opinions are building on. Pennsylvania and Philadelphia issued a joint ethics opinion in May 2024 (Joint Formal Opinion 2024-200) reaching the same place: bill for actual time, disclose AI-related costs, keep fees reasonable, and do not bill as if work done in minutes took hours. If you want to see how these opinions map across states, Justia keeps a running 50-state survey of AI ethics rules. The direction of travel is uniform. Check your own jurisdiction, and if you practice in Utah, our guide to Utah AI ethics for lawyers covers the specific authorities that govern you there.

The one thing you cannot do

There is exactly one response to AI-compressed work that is off the table, and it is worth naming plainly because it is the tempting one.

You cannot record the hours the work used to take. If a brief took you six hours last year and takes two hours now, logging six is not a rounding convenience or a value judgment. It is time you did not spend. ABA Formal Opinion 93-379 settled this in 1993, long before AI: a lawyer "may not bill more time than she actually spends on a matter," and a lawyer who reuses old work product "has not re-earned the hours previously billed." Opinion 512 restates the same idea for the AI era — a fee for which little or no work was performed is an unreasonable fee.

Do it knowingly and you have moved past a Rule 1.5 problem. Recording time you did not work is a misrepresentation to the client, and Model Rule 8.4(c) makes conduct involving dishonesty, fraud, deceit, or misrepresentation professional misconduct in its own right. The efficiency AI gives you is real. Billing it as hours is fraud framing waiting to happen. The good news is that the honest responses pay better than the dishonest one anyway.

The honest responses, with the math

AI breaks the link between hours and value. The billable hour worked because time was a decent proxy for value; AI severs the proxy. The work still has the same worth to the client, it just costs you less time to produce. The question is who captures that gap, and the rules leave you three legitimate ways to answer.

Take a solo who bills $250 an hour. A standard research-and-analysis memo used to take five hours: $1,250 of work. With AI-assisted research and a first draft, the same memo now takes two hours of genuine attorney time, including careful verification. Bill honestly and that memo is now $500. The $750 difference is the gap. Here is how to keep it without lying about it.

1. Bill fewer hours and win on volume. The straightforward path. You bill the two hours, the memo costs the client $500 instead of $1,250, and you have freed three hours to take another matter. Two honest memos in a day now earn what one padded memo would have, and you are the firm whose bills went down when everyone else's stayed suspiciously flat. In a market where clients compare invoices, cheaper-and-faster is a moat, not a sacrifice. This is where AI most obviously pays for a small shop, a point we work through in where AI actually pays for solo practitioners.

2. Move to flat fees. AI makes predictable work predictable, and predictable cost is the exact condition a flat fee needs. Quote a fixed price for a defined deliverable — say $900 for that memo type — and you have decoupled your revenue from your clock. Work faster and you keep the surplus, legitimately, because you are charging for the finished work, not for hours logged. The guardrail: the fee still has to be reasonable under Rule 1.5, judged by the value and result rather than the hours you would once have billed. Opinion 512 warns specifically against keeping an old flat fee unchanged when AI now does most of the work. Price to the deliverable, not to your former timesheet in disguise, and you are on solid ground.

3. Price to value. For work where the outcome dwarfs the hours — a contract that prevents a dispute, a filing that saves a deadline — the hours were always a poor measure. AI just makes that obvious. Value-based pricing charges for the result and the risk you carry, within Rule 1.5's reasonableness limits. It is the hardest of the three to execute and the most durable, because it does not erode every time the tools get faster.

Here is the same choice as a table.

Notice what all three honest answers have in common. None of them pretends the AI is a junior associate whose hours you get to keep billing. They compete on being faster, cheaper, or more valuable — the things clients actually want — instead of hiding the efficiency inside a padded invoice they may eventually notice.

Write it into your engagement letter and your firm policy

Two documents keep this out of trouble.

Your engagement letter should say how you bill and, if you plan to pass through any AI-specific cost, disclose that basis before the work starts. Opinion 512's expense rules turn on advance disclosure; a line in the retainer is the cheapest compliance you will ever buy.

Your firm AI policy should have a billing paragraph, not just a citation-verification paragraph. Most policies we see cover hallucinations and confidentiality and forget the invoice, which is the part that touches every client every month. Our law firm AI policy template includes a billing section anchored to these same rules, and it pairs with the broader question of whether lawyers can use AI for legal research at all. Adoption is no longer the outlier — the numbers on how many firms now use AI mean your billing practice will be compared against peers who have already worked this out.

The bottom line

Can lawyers bill for AI work? Yes, for the time they actually spend, and not a minute more. Opinion 512 and Rule 1.5 close the dishonest door — you cannot bill yesterday's hours for today's speed — and leave three honest doors wide open: bill fewer hours and win on price, move to flat fees and keep the surplus you earn by working faster, or price to the value you deliver. The firms that pick one of those on purpose, and say so in writing, turn AI's awkward billing question into a competitive edge. Predictable pricing is easier to offer when your own costs are predictable, which is part of why we publish flat, transparent plans instead of per-seat database contracts priced like the legacy research tools.

Whatever you bill and however you price it, the citations in the work still have to be real. Before anything AI touched goes out the door, run it through our Hallucination Shield: paste the text, and each citation it finds (up to 25 per run) is checked for existence and support, free, no signup. The billing question is about the hours. The Shield is about the one thing no pricing model can paper over — being right.

Frequently asked questions

Can lawyers bill for AI work? Yes, but only for the time you actually spend, not the time the AI saved. Under ABA Formal Opinion 512 and Model Rule 1.5, a lawyer billing hourly must bill actual time worked. If a task that took five hours now takes ninety minutes with AI plus review, you bill ninety minutes. Charging the old hourly total for the faster work is an unreasonable fee, not an efficiency gain.

Can a lawyer bill clients for time spent learning an AI tool? Generally no. ABA Formal Opinion 512 says lawyers may not charge clients for time spent learning to use a generative AI tool they will use regularly in their practice, because a lawyer may not bill for time made necessary by their own inexperience. The one exception is when a specific client asks you to use a particular tool you do not know; learning that tool for that matter may be billable.

Can lawyers charge clients for the cost of an AI subscription? A general subscription used across your whole practice is overhead and cannot be billed separately without a prior agreement. Opinion 512 treats it like the cost of equipping an office. A per-use, third-party AI charge incurred for one matter can be passed through as an out-of-pocket expense at actual cost, with no surcharge, and only if you disclose the basis to the client, preferably in writing.

Is it fraud to bill pre-AI hours for work AI did faster? Knowingly billing hours you did not work is not a pricing strategy. ABA Formal Opinion 93-379 says a lawyer may not bill more time than actually spent, and Model Rule 1.5 forbids an unreasonable fee. Recording time you did not spend is a misrepresentation, and at scale it can implicate Rule 8.4(c), which makes dishonesty, fraud, deceit, or misrepresentation professional misconduct. Bill the real time or move to a flat fee.

Should small firms switch to flat fees because of AI? Often yes. AI makes the cost of predictable work predictable, which is exactly the condition flat fees need. A flat fee lets you keep the surplus from working faster without padding an hourly bill. The fee still has to be reasonable under Model Rule 1.5, judged by the value and result rather than by the hours you would have logged, so price to the work delivered, not to yesterday's timesheet.