> ## Documentation Index > Fetch the complete documentation index at: https://docs.dualentry.com/llms.txt > Use this file to discover all available pages before exploring further. # Books Reference > Reference for DualEntry Books: Book fields and limits, which Books each record type posts to, the report Book filter, and the API, CLI, and MCP coverage. This page lists the fields, limits, and rules for Books in one place. For how Multi-Book works, see [Multi-Book Accounting](./index); for the steps, see [How to Set Up and Manage Books](https://docs.dualentry.com/accountants/platform-configuration/multi-book/set-up-books.md) and [How to Assign Books to Records](https://docs.dualentry.com/accountants/platform-configuration/multi-book/assign-books-to-records.md). ## Book fields A Book has the fields below. You set them on the **New Book** drawer under **Configuration → Accounting Setup → Books**, and the API returns them under the names shown. | Field | API name | Type | Required | Default | Description | | - | - | - | - | - | - | | **Name** | `name` | string | Yes | None | The name shown in Book selectors, report filters, and record Activity. Editable, including on the Primary Book. | | **Code** | `code` | string | Yes | None | A short identifier of up to 20 characters, unique in the organization across active and inactive Books. Stored in uppercase. Can't be changed after the Book is created. | | **Description** | `description` | string | No | Empty | Free text describing the Book. | | **Status** | `is_active` | boolean | No | Active (`true`) | Whether new records can go to the Book. Inactive Books keep their existing records. | | Not shown | `is_default` | boolean | N/A | `false` | `true` for the Primary Book only. Shown in the app as **Primary** next to the Book's name. | | Not shown | `id` | integer | N/A | Assigned | The Book's identifier, used in `book_ids` on records. | ## Limits and Primary Book rules The rules below apply to every organization with Multi-Book. | Rule | Value | | - | - | | Active Books per organization | Five at most, including the Primary Book. Reactivating a Book counts toward the limit. | | Primary Book | Exactly one, created automatically with the name **Primary** and the code `PRIMARY`. It can be renamed but not deactivated, and it can't receive a historical records sync. | | Deleting a Book | Not available. Deactivate the Book instead. | | Historical records syncs | One queued or running sync per Book. The source and the target must both be active and must be different Books. | | Currency | Books have no currency of their own. Every Book reports in your companies' currencies. | ## Which Books each record posts to The table below shows where each record type gets its Books, with the organization setting **Allow Book selection on all records** off (the default) and on. "All active Books" means every Book that is active when the record is created. | Record type | Setting off | Setting on | | - | - | - | | Journal entry | The Books you select, or all active Books if you select none. | Same as setting off. | | Invoice, bill, customer or vendor payment, customer or vendor credit, refund, prepayment, prepayment application, deposit, cash sale, direct expense, bank transfer, intercompany journal entry, allocation journal | All active Books. | The Books you select, or all active Books if you select none. | | Contract | All active Books. | The Books you select, or all active Books if you select none. | | Records a contract generates: linked invoices, customer credits, change orders, terminations, adjustments, revenue recognition entries | The contract's Books. | The contract's Books. | | Amortization (prepaid expense) | All active Books. | The Books you select, or all active Books if you select none. | | Amortization schedule entries | The amortization's Books. | The amortization's Books. | | Fixed asset | All active Books. | All active Books. | | Depreciation, disposal, and revaluation entries | The fixed asset's Books. | The fixed asset's Books. | | Inventory transactions | All active Books. | All active Books. | | Reversing and elimination entries | The Books of the record they belong to. | The Books of the record they belong to. | | Records created by CSV import or bulk import | All active Books. | All active Books. | Two rules apply on top of the table: * **Linked records match**: a payment, refund, or prepayment application must have exactly the same Books as every posted record it applies to. Drafts aren't checked until they're posted. * **Changes after creation**: with the setting off, only journal entries can change to a different set of Books. Changing a contract's Books changes the Books on every record it generated. ## Reports and the Book filter Reports that read general ledger data have a **Book** filter. It lists active Books, with the Primary Book first and marked **(Primary)**. When you don't choose a Book, the report shows the Primary Book. The table below groups reports by how they use Books. | Report group | Book behavior | | - | - | | Income statement, balance sheet, statement of cash flows, trial balance (summary and detail), GL detail, AR aging, AP aging, and other reports built on general ledger data | Filtered by the **Book** you choose, or the Primary Book by default. | | Fixed asset register and fixed asset rollforward | Filtered by depreciation book, not by GL Book. | | Inventory valuation, inventory activity, three-way match, revenue waterfall, invoice waterfall, ARR by contract, ownership reports, withholding tax register | Not affected by Books. | The filter takes one Book at a time. For why there is no combined view, see [Reporting by Book](./index#reporting-by-book). ## Record Activity Changes to a record's Books appear in its **Activity** as "Books from" the previous Books "to" the new Books, with Book names. An empty side shows as "(none)". | Event | Logged in record Activity | | - | - | | Books changed on a record | Yes, when the set of Books actually changes | | Books changed on a contract | Yes, once on the contract, not on each record it generated | | Historical records sync | No. Each run appears in the Book's sync history instead. | | Book assignments made before Book changes were logged | No | ## API, CLI, and MCP The public API reads Books and sets them on journal entries and contracts. Each endpoint below is also available under `/public/v3-alpha/`. | Endpoint | What it does with Books | | - | - | | [`GET /public/v2/books/`](https://docs.dualentry.com/developers/api/resources-v2/books/list-books) | Lists Books with `id`, `code`, `name`, `description`, `is_default`, and `is_active`. Filter with `search`, `id`, `code`, and `is_active`. | | `GET /public/v2/books/{book_id}/` | Returns one Book. | | `POST /public/v2/journal-entries/` | Accepts `book_ids`, an array of Book IDs. Omit it or send `null` or an empty array to post to all active Books. | | `PUT /public/v2/journal-entries/{record_number}/` | Accepts `book_ids` the same way. Omitting it assigns all active Books, so send the full list on every update to keep a selection. | | `PUT /public/v2/contracts/{record_id}/` | Accepts `book_ids`. A changed set is rejected while **Allow Book selection on all records** is off. | | `POST /public/v2/contracts/` and `POST /public/v2/invoices/` | Don't accept `book_ids`. A new contract goes to all active Books, and an invoice goes to all active Books or, when it's linked to a contract, to the contract's Books. | Journal entry, contract, contract change order, and revenue recognition responses include `book_ids`. Other record types don't take or return Books through the public API, so they get their Books by the rules in [Which Books each record posts to](#which-books-each-record-posts-to). The API returns these validation errors under the `book_ids` key: * `Select exactly the same books as every posted linked record.` * `Book selection is disabled for this organization.` * `All selected books must be active and belong to this organization.` ### CLI and MCP The [DualEntry CLI](https://docs.dualentry.com/developers/guides/cli/reference.md) has no command for Books. `dualentry depreciation-books` lists fixed asset depreciation books, such as `BOOK` and `FEDERAL`, which are separate from GL Books. The [DualEntry MCP server](https://docs.dualentry.com/accountants/ai-automation/mcp/mcp-integration.md) has no Book-specific tool. ## Related pages * [Multi-Book Accounting](./index): how Books and Book assignment work * [How to Set Up and Manage Books](https://docs.dualentry.com/accountants/platform-configuration/multi-book/set-up-books.md): create, sync, and deactivate Books * [How to Assign Books to Records](https://docs.dualentry.com/accountants/platform-configuration/multi-book/assign-books-to-records.md): choose and change Books on records * [Aging Reports Reference](https://docs.dualentry.com/accountants/reporting-analytics/aging-reports.md): AR and AP aging, which respect the **Book** filter This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.