The 8 best private AI tools for accountants in 2026
Chosen for one question before any other: where does the client's data go? Then for what each tool is actually good at in a practice.
Short answer
If client files may go to a vetted cloud provider under contract, use a business plan that excludes training by default: ChatGPT Business or Enterprise, Microsoft 365 Copilot, or Claude Team or Enterprise. If they must stay in the office, run models locally: OpenClerq for recurring checks with exact calculations, AnythingLLM or GPT4All to query documents, LM Studio or Jan for drafting. In neither case should a language model produce the final figures.
We build OpenClerq, which appears on this page. We have tried to describe every tool fairly and to say where another one is the better choice. Facts checked 19 September 2026; if something is wrong, open an issue.
The list at a glance
| Tool | Where client data goes | Trains on it? | Best for |
|---|---|---|---|
| OpenClerq | Nowhere, with a local model | No | Recurring checks and exact calculations with a record |
| AnythingLLM | Nowhere, with a local model | No | Asking questions across client documents |
| LM Studio | Nowhere | No | Drafting and summarising with a local model |
| Jan | Nowhere, with a local model | No | An open-source everyday assistant |
| GPT4All | Nowhere | No | Document questions on modest hardware |
| ChatGPT Business / Enterprise | OpenAI, under contract | Not by default | General drafting, analysis of uploaded spreadsheets |
| Microsoft 365 Copilot | Microsoft 365 service boundary | Not used for foundation models | Practices that work in Excel, Outlook and Teams |
| Claude Team / Enterprise | Anthropic, under contract | Not by default | Long documents and careful writing |
Nothing leaves the office
01OpenClerq
- Best for
- Month-end checks, VAT and reimbursement calculations, anything run on a schedule
- Licence
- MIT, free
Our product. Formulas — net = gross / 1.25, vat = gross - net — run in a deterministic engine that returns a proof record; the model only explains. Scheduled and file-triggered runs are recorded with the model, tokens and cost of every call. Use a local model through Ollama or LM Studio, or a cloud model under your own key where your rules allow.
Watch out: early software (release 0.5). It reads plain-text exports, not PDFs, and has no accounting-software integrations; you write the formulas, or commission a module through Clerq for Business.
02AnythingLLM
- Best for
- Questions across engagement letters, policies and client correspondence
- Licence
- MIT, free
Put documents into a workspace per client and ask questions of them with a local model. The desktop app keeps everything on the machine.
Watch out: answers come from retrieved snippets; check them against the source.
03LM Studio
- Best for
- The easiest start with a local model
- Licence
- Proprietary, free for home and work
Download a model sized for your computer and use it to draft client letters, summarise notes and rewrite explanations in plain language. It can also serve that model to OpenClerq.
Watch out: closed source, and no audit trail beyond chat history.
04Jan
- Best for
- An open-source everyday assistant for the practice
- Licence
- Apache 2.0, free
A ChatGPT-style app that runs local models. Cloud models can be added, so be clear with staff which ones are allowed for client work.
05GPT4All
- Best for
- Private document questions on an older laptop
- Licence
- MIT, free
Runs without a graphics card, and its LocalDocs feature indexes a folder on the device so you can ask questions of it offline.
Cloud, under contract
06ChatGPT Business and Enterprise
- Data
- Not used for training by default; admin controls
- Price
- Per user, per month
The strongest general assistant, with analysis of uploaded spreadsheets, admin controls and single sign-on on higher tiers. Business was formerly called Team.
Watch out: the data does go to OpenAI; check retention and the data processing agreement, and make sure nobody uses a personal account instead. OpenClerq vs ChatGPT.
07Microsoft 365 Copilot
- Data
- Processed inside the Microsoft 365 service boundary; not used to train foundation models
- Price
- Paid add-on per user
AI inside Excel, Word, Outlook and Teams, grounded in the practice's own Microsoft 365 data, with Purview audit and retention.
Watch out: Copilot can surface anything a user has access to. Tidy SharePoint and OneDrive permissions before switching it on. OpenClerq vs Copilot.
08Claude Team and Enterprise
- Data
- Not used for training by default under Anthropic's commercial terms
- Price
- Per user, per month
Strong with long documents — engagement letters, contracts, regulations — and with careful, well-structured writing.
Watch out: a cloud service; the same contract checks apply as for ChatGPT.
What an accountant should never hand to a language model
- Final figures. Use a spreadsheet formula or a calculation engine; let the model explain. See how to stop AI getting numbers wrong.
- Filing and payment decisions. A person approves every submission.
- Unchecked classification. A suggested ledger code is a suggestion until someone reviews it.
- Anything your engagement letter restricts. Read it before choosing a cloud tool.
A sensible setup for a small practice
- One cloud business plan for non-confidential work — research, drafting templates, internal notes — on company accounts only.
- A local model for anything containing client data, run through LM Studio or Ollama.
- Formulas in one place, evaluated deterministically, with a record of every run.
- A written policy: which data goes where, who approves, and how often you review it.
Frequently asked questions
Can accountants use ChatGPT with client data?
Check your professional body's guidance and your engagement letters first. On a Business or Enterprise plan, data is not used for training by default and sits under a contract; on a personal plan it is used for training unless switched off. For the most sensitive material, a local model is simpler.
What is the most private way for an accountant to use AI?
A model running on the practice's own computers, so client data is never uploaded. OpenClerq, AnythingLLM, LM Studio, Jan and GPT4All all work this way.
Can AI do my bookkeeping?
It can suggest categories, draft explanations and flag anomalies. Final figures, reconciliations and filings need deterministic tools and a person's approval.
Is Microsoft 365 Copilot safe for accounting firms?
It keeps processing inside Microsoft 365 and does not train foundation models on your data. The practical risk is oversharing: Copilot can find anything a user has permission to see, so review permissions first.