The Crossing Report — Issue #3 | March 26, 2026

AI and Client Billing: How Law and Accounting Firms Should Price Services When AI Does the Work

Published March 26, 2026 · By The Crossing Report · 8 min read

Summary

61% of corporate clients are now somewhat or very likely to question their firm's pricing model because of AI. Meanwhile, 34% of law firms using AI are charging premium rates for AI-enhanced work, while only 6% are passing savings to clients — and 59% of in-house professionals say they've seen no noticeable savings from their firms' AI use. ABA Formal Opinion 512 (2024) and state bar opinions from Texas, California, and Florida have now established specific rules: you cannot bill for time AI eliminated, must disclose AI use in billing contexts, and must update your engagement letters. This guide covers what the rules require, how to price AI-assisted work fairly, and how to have the client billing conversation proactively.

The Client Billing Problem AI Creates

AI is breaking the premise of hourly billing: that you can't know in advance how long something takes.

When AI makes your workflows consistent and predictable, you can price them that way. But that efficiency creates a client expectation problem. According to recent industry surveys:

  • •61% of corporate clients are now “somewhat” or “very” likely to question their firm's pricing model in light of AI
  • •46% of clients don't think they should pay the same rates when AI does the work
  • •59% of in-house professionals say they've seen “no noticeable savings” from their firms' AI use
  • •34% of law firms using AI are actually charging premium rates for AI-enhanced work; only 6% pass savings to clients

That gap is a ticking clock. The firms that handle this proactively will earn trust and referrals. The ones that get caught flat-footed will lose clients.

Key Takeaway

Should law firms charge the same rate when AI does the work?

Not for time AI eliminated. ABA Formal Opinion 512 (2024) establishes that attorneys cannot bill clients for time that AI has replaced — if a task that took 6 hours now takes 90 minutes, you cannot bill the 4.5 hours that didn't happen. However, you may maintain your overall fee structure if it reflects expertise and value delivered rather than hours on tasks.

How to Price Services When AI Is Doing the Work

The pricing question has a practical answer, but it requires distinguishing between what AI replaced and what your firm's expertise actually delivers.

What you must do (per ABA Formal Opinion 512 and state bar guidance):

  • •Do not bill clients for time AI eliminated. If a task now takes 90 minutes instead of 6 hours, you cannot bill for the 4.5 hours that didn't happen.
  • •If you use a per-use third-party AI service and pay a direct cost per query or document, you may pass that cost through to clients — but only with prior disclosure and agreement.
  • •Update your engagement letters to specifically address AI use. Generic boilerplate language (“we may use technology”) does not satisfy the disclosure requirement.

What you do not have to do:

  • •You do not have to lower your overall fees because AI makes you faster. You are being paid for expertise and outcomes, not hours. Reframing around value is both ethical and appropriate.
  • •Subscription AI tools embedded in your practice software (Karbon, Clio, etc.) are overhead — like rent. They are not billable as expenses to clients.

Key Takeaway

What does the ABA say about billing for AI-assisted work?

ABA Formal Opinion 512 (2024) prohibits billing clients for time AI has replaced. It also requires disclosure when AI use relates to justifying fees — boilerplate engagement letter language is not sufficient. Subscription AI tools embedded in practice management software are overhead and not billable to clients; direct per-use AI costs may be billed only with prior client disclosure and consent.

Flat Fee Pricing for AI-Assisted Legal and Accounting Work

When AI makes your workflows consistent and predictable, flat-fee pricing becomes viable — and clients prefer it.

71% of clients already prefer flat fees over hourly billing. The data on flat fee economics is compelling:

  • •Flat fee matters close 2.6x faster than hourly matters
  • •Payments arrive nearly twice as quickly
  • •Alternative fee arrangements (AFAs) were projected to hit 70% of law firm revenue by 2025, up from 20% in 2023

Three flat-fee models that work:

Model 1: The Hybrid (Most practical for 2026)

Keep hourly billing for complex, variable, judgment-intensive work. Convert high-volume, predictable, AI-assisted work to flat fees.

Law examples:

  • •Standard residential real estate closing: $1,500 flat
  • •Routine employment contract review: $600 flat
  • •Complex litigation: hourly

Accounting examples:

  • •Monthly bookkeeping + reconciliation (up to 200 transactions): $400/month flat
  • •Standard individual tax return (W-2, standard deductions): $350 flat
  • •Business tax with complexity: hourly or scoped engagement

Model 2: The Value Retainer

Replace hourly billing for ongoing clients with a fixed monthly advisory fee. AI handles the routine work; you show up as the strategic advisor. Price it by estimating average monthly hours over the past year, apply your hourly rate, reduce 10–20% to reflect efficiency gains.

Model 3: The Itemized AI Credit

Continue billing hourly but explicitly credit clients for AI-generated time savings. Example: “Contract clause extraction: AI processed initial review [2.0 hrs of prior equivalent time]; attorney review and final markup: 0.5 hrs at $X/hr.” Transparent, builds trust, satisfies sophisticated clients who will ask anyway.

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Key Takeaway

How do I price flat fees for AI-assisted legal work?

Identify a service line where AI has made your time cost consistent and predictable. For routine work (standard closings, contract reviews, recurring tax returns), calculate your average time cost at your current rate. Reduce by 20–30% to reflect efficiency, quote as a flat fee. Track margin for 90 days. Most firms find the margin improves significantly once they stop pricing work at cost-plus-hours.

What Bar Associations and CPA Boards Say About AI Disclosure

The ethics guidance is no longer theoretical. Here is what you are required to do.

ABA Formal Opinion 512 (July 2024)

The ABA's first formal guidance on generative AI. Key obligations:

  • •Disclose AI use when it relates to justifying fees
  • •Obtain specific informed client consent (not boilerplate) before processing client data in AI tools
  • •Do not bill for time AI eliminated
  • •Subscription AI tools embedded in practice software are overhead — not billable

Texas State Bar, Ethics Opinion No. 705 (February 2025)

Lawyers must not charge clients for time saved by AI. Must disclose AI use that affects billing.

California (2025)

Lawyers must inform clients in writing of intent to charge direct AI costs. Client consent required before sharing data with AI platforms.

Florida

Disclosure required when AI use impacts client billing.

AICPA (ET §1.300.040)

The existing third-party service provider rule already applies to AI tools processing client data. Informed consent and confidentiality controls are required. CPA.com has issued specific AI guidance reinforcing these obligations.

The standard that is emerging

Update your engagement letters before a client asks. A clear, plain-language paragraph addressing AI use is now table stakes for any professional services firm operating in 2026.

Key Takeaway

What are the ethics rules around AI billing for accountants?

The AICPA's ET §1.300.040 (third-party service providers) requires accountants to ensure informed consent and confidentiality controls when AI tools process client data. Accountants may not bill clients for time AI replaced, and subscription AI tools embedded in practice management software are overhead — not billable as client expenses.

FAQ — AI Billing and Client Transparency

Should law firms charge the same rate when AI does the work?

No, not for time AI has replaced. ABA Formal Opinion 512 (2024) and Texas Ethics Opinion 705 (2025) both prohibit billing clients for time AI eliminated. However, law firms are not required to reduce their overall professional fee structure simply because AI improves efficiency — fees may continue to reflect expertise and value delivered.

What does the ABA say about billing for AI-assisted work?

ABA Formal Opinion 512 (July 2024) establishes three key rules: (1) do not bill for time AI replaced; (2) disclose AI use when it relates to justifying fees — boilerplate engagement language is insufficient; (3) subscription AI tools embedded in practice management software are overhead and not billable to clients. Direct per-use AI costs may be passed to clients only with prior written disclosure and agreement.

Do I need to disclose to clients when I use AI?

Yes, in specific circumstances. ABA Formal Opinion 512 requires disclosure when AI use relates to fee justification. Texas, California, and Florida bar guidance require written disclosure when AI impacts billing or when client data is being processed by AI tools. The AICPA ET §1.300.040 requires informed consent before sharing client data with third-party AI services. As a practical matter, updating your engagement letter to address AI use proactively is the lowest-cost compliance path.

How do I price flat fees for AI-assisted legal work?

Start with a high-volume, consistent service line where AI has made your time cost predictable. Calculate your average time cost over the past year at your current rate. Reduce by 20–30% to reflect AI efficiency gains. Quote as a flat fee. Track margin for 90 days. For complex or variable work, keep hourly billing — flat fees require consistent scope to price confidently.

What are the ethics rules around AI billing for accountants?

The AICPA's existing ET §1.300.040 (third-party service provider) rule applies to AI tools that process client data — accountants need informed consent and must ensure confidentiality protections are in place. Subscription AI tools embedded in practice management software (Karbon, TaxDome) are overhead costs, not billable client expenses. The Journal of Accountancy (February 2026) identified shadow AI and billing transparency as top CPA compliance risks.

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