Case study · Accounting and tax · Claude Enterprise plan
An accounting firm would only let AI near tax data with zero data retention, so we planned a setup that never leaves it
A small US accounting firm wanted Claude to help through tax season, on one condition: client tax data could only reach an AI service that keeps none of it. We worked out what that condition rules in and out, and planned a setup where Claude reads each client's documents on the firm's own server and fills the tax software's own import files, with no live connection.
- Client
- An accounting firm in the United States
- Industry
- Accounting and tax
- Users
- Six CPAs, each on their own office PC
- What we did
- A paid Stage 1 assessment: the options, the compliance points, the connection to the tax software and a step-by-step plan
- Built on
- Claude Enterprise with zero data retention, Claude Code on each PC, and CCH Axcess Tax's own import templates
- AI in the product
- Claude Enterprise with Claude Code
- Status
- Stage 1 plan prepared, November 2026. Nothing has been built yet.
- 6PCs in the plan, all set up the same way
- 0client files used until zero retention is confirmed in writing
- 1filed prior-year return rebuilt by import and compared line by line as the pilot
- 4meetings in the whole plan
These are the plan's own terms. No results are claimed until the pilot runs.
The problem
The owner's ideal was a draft return filled in from the documents already on the firm's server, and he gave it even odds of working. Three facts made it hard. Zero data retention covers Claude Code on an Enterprise plan, but it does not cover the chat or desktop apps, or any data that passes through a connector or an MCP server. The firm's tax software, CCH Axcess, has no ready-made Claude connector, and a live link would need a paid API licence and custom programming. And tax preparers carry their own duties on client data, from section 7216 to the IRS's June 2026 guidance on AI in tax practice.
What we did
Every route checked against the one condition.
We compared the ways the firm could run Claude, from the standard plans to running it through a cloud provider, and checked each one against Anthropic's own documentation on zero data retention. The firm chose Claude Enterprise with zero retention, with Claude Code on each PC.
Import files in place of a live link.
Claude reads a client's folder on the server, read only, and fills CCH Axcess's own Excel import templates, showing the page each figure came from. Staff check the figures and run the import. Claude does not prepare returns or make tax decisions; review and signing stay with the firm's CPAs.
PCs locked to the firm's account.
One settings file on every PC locks sign-in to the firm's Enterprise organization, turns off non-essential traffic and lets Claude save only to one outputs folder. Claude sees the client folders through a read-only drive, while staff keep their normal access.
The compliance steps in the plan.
The firm decides with its counsel how section 7216 is handled, and adds Anthropic to its written information security plan as a service provider. Seats are bought only after Anthropic confirms in writing that the firm qualifies for zero retention.
A pilot that proves it on a real return.
The pilot runs on the owner's PC: one filed prior-year individual return is rebuilt by import and compared with the filed one line by line, then a trust return. Only then does the firm's IT provider copy the setup to the other five PCs.
How a client file moves
Does your client data need zero retention before AI can touch it?
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