> For the complete documentation index, see [llms.txt](https://www.zerabooks.com/help/llms.txt).
# Invoice accounting settings
Tell ZeraBooks which accounts invoices post to — Accounts Receivable, sales tax, holdback and settlement differences — and when documents post on their own.
## Open the settings
1. Go to **Bills & Invoices** › **Invoices**.
2. Click **More Actions** (the three dots) at the top of the board.
3. Choose **Invoice accounting settings**. The **Bills & invoices settings** dialog opens.
The same dialog serves bills and invoices. "ZeraBooks never guesses which account is which." Name each account once and every invoice, payment and receipt uses it.
## What each section does
| Section | Field for invoices | What it's for |
| --- | --- | --- |
| **Control accounts** | **Accounts Receivable** (required) | What customers owe you. Every approved invoice debits it. |
| **Sales tax** | **Tax charged on sales** | Tax you collect, held for the government. Must be a liability account. Declaring it adds a **Tax** field to invoice lines. |
| **Holdback (retainage)** | **Holdback receivable** | Money a customer holds back from you until a job is finished. Must be an asset account. Declaring it adds a **Retainage / holdback** field to invoices. |
| **Settlement differences** | **Settlement shortfalls** and **Settlement overages** | Where the gap posts when a payment doesn't match the invoice. A short payment goes to shortfalls (an expense, usually bank charges); an overpayment goes to overages. ZeraBooks picks the account by whether the payment was short or over. |
The other fields in each section (**Accounts Payable**, **Tax paid on purchases**, **Holdback payable**) are for bills. Under each field, ZeraBooks explains why the account has to be that type, and flags a choice that doesn't fit.
## Declared tax treatments
Add each tax you expect to see printed on documents with **Add tax**: its printed code or name (for example `GST`), **Rate %** and the dates it applies from and through. ZeraBooks matches the printed name, rate and date on uploaded documents. You can declare up to 32. With none declared, "a document with printed tax will wait for review until its exact treatment is configured here."
## When to post automatically
The checkbox **Post bills from vendors I already use** is the same switch as Autopilot's **Approve bills and invoices**. Turning it off here also turns it off on the **Autopilot** page, and then no uploaded invoice or bill posts without your click.
## Home currency
Shows the company's books currency. To change it, click **Change it in Manage Clients**. An invoice in another currency posts at its date's exchange rate once its currency is confirmed; payment differences land on Exchange Gain or Loss.
Click **Save settings** when you're done. If something is wrong, the dialog says which field and nothing is changed.
## Frequently Asked Questions
Where do I set the sales tax account for invoices?
In **Bills & invoices settings** › **Sales tax** › **Tax charged on sales**. Until it's set, an invoice with tax is refused: "This invoice has tax on a line, but no account is declared for tax charged on sales."
What's the difference between the Bills and Invoices settings?
There's one dialog for both. Opened from Invoices, **Accounts Receivable** is marked required; opened from Bills, **Accounts Payable** is.
Why can't I pick a certain account?
Each field only accepts the right type of account. Accounts Receivable must be an asset, tax charged on sales a liability, holdback receivable an asset. A deactivated account can't be chosen either.
Can I change an account after invoices have posted to it?
Not while posted invoices or payments use it. ZeraBooks says the account "is already used by posted documents or settlements" and asks you to release those first.
What is retainage (holdback)?
Part of an invoice the customer holds back until the job is finished, common in construction. ZeraBooks posts it to **Holdback receivable** instead of Accounts Receivable, so it's tracked apart from what's due now.
Why does the message say "declare it in Bills settings" when I'm on an invoice?
Bills and invoices share one settings dialog. Open it from the Invoices board with **More Actions** › **Invoice accounting settings**.
---
## Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://www.zerabooks.com/help/invoices/invoice-accounting-settings.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.
The full index is at https://www.zerabooks.com/help/llms.txt. An MCP server with `searchDocumentation`, `getPage` and `askQuestion` tools is at https://www.zerabooks.com/help/mcp.