Can AI post entries to Xero, QuickBooks or FreeAgent safely?

Why letting AI write to your books needs care

Reading your books is low risk: the worst a wrong answer does is mislead you, and you can check it. Writing is different. An entry that lands in the wrong account, the wrong period or against the wrong supplier flows into your VAT return, your management accounts and your year-end figures.

A general AI tool with write access can go wrong in three ways. It can invent a plausible account code that does not exist. It can misread what you asked for. And it can be steered by text it reads, such as instructions hidden in a supplier’s invoice, which security guidance calls prompt injection. Safe posting is designed around all three.

How approved posting works in Nella

1. You describe the entry in plain English in ChatGPT or Claude: “Add Tuesday’s £180 bill from the builders’ merchant to repairs.”
2. Nella builds the entry, not the AI. Nella matches each name to exactly one record in your own books (the supplier, the account, the tax code) and builds the entry itself. A request that tries to supply raw debits and credits is refused.
3. Checks run before you see it. An entry that breaks a hard rule is refused and nothing is stored. Softer concerns, such as a possible duplicate, appear as warnings you must tick before you can approve.
4. You see the whole entry on a card: the supplier, the accounts, the tax, the total and any warnings.
5. You press the card’s button. Typing “yes” in the chat is not enough. If you change anything, Nella shows a new card.
6. Nella posts that entry and nothing else, then reads it back from your books to confirm it landed as shown.
7. There is a record and an undo. Each approval is recorded with what it approved. Where your software allows, the entry can be undone from the card.

Each post carries its own approval. There is no standing permission for Nella to post whatever it decides.

What you can post

A few types are specific to one platform: batch payments and projects on Xero, expense and mileage claims on FreeAgent, and sales receipts on QuickBooks.

What Nella never does

• It moves no money. Recording a payment records what happened at the bank. It does not pay anyone.
• It files nothing with HMRC, the IRS, the ATO or Companies House.
• It does not decide treatment. Whether a cost is allowable, or VAT or GST can be claimed, is a question for your accountant. For UK and Australian businesses, doubts about a supplier’s VAT or GST registration appear as a warning on the card; the decision stays with you.

Which software, and which plan

Approved posting works with Xero, QuickBooks and FreeAgent, through the Nella connector in ChatGPT and Claude. Sage is not yet included. It is part of Nella Pro and is being switched on for existing users with Nella’s updated terms. Reading your books needs only the permission you gave when you connected; posting also needs your permission in Nella, and every entry its own approval.

Example · illustrative figures

An owner uploads a £180 receipt from a building supplier and asks Nella to add it to repairs. The card shows the supplier from the books, the repairs account, VAT of £30 and a total of £180. It also shows a warning: a bill for the same amount from the same supplier was entered two days earlier. The owner checks, finds it is a second visit, ticks the warning and approves. Nella posts the bill to Xero and confirms it in the books.

Read-only versus write access

Most AI finance tools only read. That covers most of the value: answering questions, flagging issues and drafting work. Write access adds speed for routine entries, and is safe only with per-item approval, a full preview and an undo. For the wider picture of permission levels, see AI finance agents and human approval.

Related: Can AI check supplier bills before I pay them? and Are my books ready to close?

Sources

• Claude Help Center: Get started with custom connectors using remote MCP
• Model Context Protocol specification: Authorization

Nella provides financial information and education, not accounting or tax advice. Nella shows you the numbers. When a question needs professional judgement, such as a filing or a tax decision, Nella says so and points you to a qualified accountant.