---
title: "Compare a draft invoice with the engagement letter and later fee communications"
url: "https://ailawframework.com/obligations/costs-billing-and-litigation-funding/compare-a-draft-bill-to-the-last-costs-disclosure-and-any-updates/united-states"
type: "task_jurisdiction_version"
site: "AI Law Framework"
id: "A42-A20260923-2-US"
practice_area: "Costs, billing & litigation funding"
tier: "yellow"
lawyer_review: "required"
jurisdictions: ["US"]
last_reviewed: "2026-10-22"
---

# Compare a draft invoice with the engagement letter and later fee communications

> Set the draft invoice beside the engagement letter and any later writing that changes the rate, scope or expenses, and list every line that does not match.

Canonical page: https://ailawframework.com/obligations/costs-billing-and-litigation-funding/compare-a-draft-bill-to-the-last-costs-disclosure-and-any-updates/united-states  
Last reviewed: 2026-10-22

Site index for agents: https://ailawframework.com/llms.txt

## Key facts

| Fact | Value |
| --- | --- |
| Practice area | [Costs, billing & litigation funding](https://ailawframework.com/obligations/costs-billing-and-litigation-funding.md) |
| Human involvement | Yellow: Lawyer and AI draft together |
| How AI is used | Set the draft invoice beside the engagement letter and any later writing that changes the rate, scope or expenses, and list every line that does not match. |
| What the lawyer must review | Rule 1.5(b) requires a change in the basis or rate of the fee or expenses to be communicated to the client. A line that uses a rate or expense the client was not told about is a Rule 1.5 problem, not a formatting problem. Formal Opinion 512: before charging for a generative-AI tool, explain the basis for the charge, preferably in writing. Do not treat general tool overhead as a disbursement unless that was disclosed in advance. |
| Written for | United States |
| Applies to | [Compare a draft bill to the last costs disclosure and any updates](https://ailawframework.com/obligations/costs-billing-and-litigation-funding/compare-a-draft-bill-to-the-last-costs-disclosure-and-any-updates.md) |

## Checking plan

- What the AI does: Set the draft invoice beside the engagement letter and any later writing that changes the rate, scope or expenses, and list every line that does not match.
- Basis: Checked against the linked sources on 22 October 2026. Confirm the current instrument before reliance.

## Notes

- Opinion 512 treats a tool that functions like ordinary office equipment as overhead. A per-use third-party charge for a particular client can be a disbursement at actual cost, without a surcharge, unless the engagement says otherwise.
- Confirm the state version of Rule 1.5. Some states require the fee agreement itself to be in writing.

## Sources

- [ABA Model Rule 1.5, Fees](https://www.americanbar.org/groups/professional_responsibility/publications/model_rules_of_professional_conduct/rule_1_5_fees/) (checked 2026-10-22)
- [ABA Formal Opinion 512, Generative Artificial Intelligence Tools (29 July 2024)](https://www.americanbar.org/content/dam/aba/administrative/professional_responsibility/ethics-opinions/aba-formal-opinion-512.pdf) (checked 2026-10-22)
- [State Bar of California, Practical Guidance for the Use of Generative Artificial Intelligence in the Practice of Law (2026 update)](https://www.calbar.ca.gov/Portals/0/documents/ethics/Generative-AI-Practical-Guidance.pdf) (checked 2026-10-22)

## Forms and precedents for this task

| Form or precedent | Kind | AI level | Summary |
| --- | --- | --- | --- |
| [Engagement letter with a generative AI clause (United States)](https://ailawframework.com/precedents/costs-billing-and-litigation-funding/us-engagement-letter-generative-ai.md) | Letter | Yellow | Engagement letter stating the scope and the basis of the fee, and separating ordinary generative-AI use from any input of information relating to the representation, which needs a completed tool… |
| [Timekeeper check before billing generative AI work (United States)](https://ailawframework.com/precedents/costs-billing-and-litigation-funding/us-timekeeper-gai-billing-check.md) | Checklist | Yellow | A check a timekeeper completes before AI-assisted time or a per-use AI charge is put on a bill, so the bill reflects time actually spent and expenses the engagement allows. |
| [Worksheet comparing a draft bill with the costs disclosure](https://ailawframework.com/precedents/costs-billing-and-litigation-funding/bill-disclosure-comparison.md) | Checklist | Yellow | Internal worksheet that sets a draft bill beside the last costs estimate, later updates, uplift and AI-assisted time, before the bill is sent. |
| [Letter when a flat fee should change because a tool did the work (United States)](https://ailawframework.com/precedents/costs-billing-and-litigation-funding/us-flat-fee-change-after-gai-use.md) | Letter | Yellow | A letter telling the client that a flat fee may no longer be reasonable because a generative AI tool has reduced the work, and asking agreement to a revised amount before further work is billed that… |
| [Progress report of legal costs incurred](https://ailawframework.com/precedents/costs-billing-and-litigation-funding/progress-report-of-costs.md) | Letter | Yellow | Written report, given without charge on a reasonable request, of the legal costs incurred to date or since the last bill, with the figures taken from the ledger. |

Signed-in accounts can read the full text of each one.

*Practice guidance for planning and review. Confirm current primary sources and the requirements of the actual matter. This is general information, not legal advice.*