--- title: Inventory Types description: "**Audience:** bookkeeper, admin · **Last updated:** 2026-06-07 · [Edit on GitHub](https://github.com/phreesoft/bizuno/edit/main/docs/04-modules-in-depth/03-inventory/01-inventory-types.md) # Inventory Types Every inventory item carries a two-letter **type code** that decides almost everything about how it behaves: whether it tracks stock quantity, whether it posts Cost of…" url: "https://www.bizuno.com/docs/inventory-types/" updated: "2026-06-18" category: Inventory --- # Inventory Types **Audience:** bookkeeper, admin · **Last updated:** 2026-06-07 · [Edit on GitHub](https://github.com/phreesoft/bizuno/edit/main/docs/04-modules-in-depth/03-inventory/01-inventory-types.md) # Inventory Types Every inventory item carries a two-letter **type code** that decides almost everything about how it behaves: whether it tracks stock quantity, whether it posts Cost of Goods Sold, whether it can have a bill of materials, and where its cost comes from. This page is the full per-code reference. > **The type is effectively permanent.** Once an item has posted transactions, > Bizuno locks its type (and its SKU and cost method) — the field becomes > read-only. Changing type after you've transacted means rebuilding the item's > history, not editing a dropdown. Pick deliberately. See > [Why the type is permanent](#why-the-type-is-permanent). --- ## The two big questions Two flags, derived from the type, drive the accounting: - **Does it track stock?** Tracked types maintain a real `qty_stock` (and on-order `qty_po` / `qty_so`). Non-tracked types are set to a nominal quantity of 1 and never decrement. - **Does it post COGS?** The constant `INVENTORY_COGS_TYPES` = `['ma','mi','ms','sa','si','sr']` lists the types that carry inventory cost and post to a COGS account when sold. Everything else expenses immediately or carries no cost at all. Get those two right for what you sell and the rest follows. --- ## The full type reference | Code | Name | Tracks stock | Posts COGS | BOM | Notes | | --- | --- | --- | --- | --- | --- | | `si` | Stock Item | ✓ | ✓ | — | The default. A physical good you buy and sell. | | `sr` | Serialized Stock | ✓ | ✓ | — | Like `si`, but each unit carries a serial number. | | `ma` | Assembly | ✓ | ✓ | ✓ | Built from component SKUs via a bill of materials. | | `sa` | Serialized Assembly | ✓ | ✓ | ✓ | An assembly whose finished units are serialized. | | `ms` | Master Stock | ✓ | ✓ | — | A template that generates variant items (`mi`) from options (size/color/…). | | `mi` | Master Stock Sub-Item | ✓ | (see note) | — | Auto-generated variant of an `ms` master. Hidden type — you don't create these by hand. | | `ns` | Non-stock | — | — | — | Bought/sold but not inventoried (drop-ship, one-offs). | | `lb` | Labor | — | — | — | Labor / hours. | | `sv` | Service | — | — | — | A service you sell. | | `sf` | Flat-Rate Service | — | — | — | A fixed-price service charge. | | `ci` | Charge | — | — | — | A miscellaneous charge line. | | `ai` | Activity | — | — | — | An activity/time line. | | `ds` | Description | — | — | — | A text-only line — no price, no cost. | | `ia` | Assembly Part | ✓ | — | — | Internal/hidden — used behind the scenes for assembly components. | > **About `mi` and `ia`.** They relate to the COGS-types machinery because they > track stock cost, but they're flagged `gl_cogs = false` — they don't post their > own COGS legs and aren't types you choose from the dropdown. `mi` is spawned by > a Master Stock item; `ia` is internal. You'll work with the other twelve. --- ## Tracked vs. non-tracked, in practice **Tracked** types (`si`, `sr`, `ma`, `sa`, `ms`, `mi`) are the inventory you count. They decrement on sale, increment on receipt, carry a cost layer in `inventory_history`, and post COGS at sale time. Their value sits on the balance sheet as an asset until sold. See [History and costing](/docs/history-and-costing/). **Non-tracked** types (`ns`, `lb`, `sv`, `sf`, `ci`, `ai`, `ds`) don't hold a real quantity — Bizuno parks `qty_stock` at 1 so they behave on documents but never deplete. They have no COGS leg; the expense (if any) is recognized when you buy the underlying thing, not when you sell the line. Use them for services, labor, freight/charge lines, and pure description rows. --- ## Type-specific behavior ### Assemblies (`ma`, `sa`) Only `ma` and `sa` can carry a **bill of materials** — the component list that defines what the finished item is built from. The BOM lives in item metadata and drives both build cost and "how many can I build" availability. Full detail in [Assemblies](/docs/assemblies/). ### Master Stock (`ms` → `mi`) A Master Stock item is **not** an assembly — it's a template. You define *options* (size, color, etc.) and Bizuno generates a child **`mi`** variant per combination, each with its own SKU and stock. You manage the master; the variants are produced from it and are hidden as a standalone type. --- ## Why the type is permanent Two safeguards enforce this: 1. **Edit lock.** When an item has any journal history, the entry form marks `inventory_type`, `sku`, and `cost_method` **read-only**. Because read-only fields aren't submitted, they can't be changed even by tampering with the form. 2. **Delete block.** You can't delete an item that has GL journal entries if it's a COGS-tracking type — its history would be orphaned. The reason is integrity: the type determines whether each past transaction posted COGS and tracked stock. Retyping retroactively would make historical postings inconsistent with the item's nature. If you truly need a different type, create a **new SKU** with the correct type and retire the old one (mark it inactive). > **Decision shortcut.** Physical thing you stock and resell → `si` (or `sr` if > serialized). Built from parts → `ma`/`sa`. Sized/colored variants → `ms`. > Service, labor, or freight → `sv`/`lb`/`ci`. Bought-to-order, never stocked → > `ns`. Pure text on a form → `ds`. --- ## Related - [History and costing](/docs/history-and-costing/) — how tracked types are costed - [Assemblies](/docs/assemblies/) — `ma`/`sa` bills of materials - [Inventory types and COGS](/docs/inventory-types-and-cogs/) — the concept - [Journals (the journal_id reference)](/docs/journals/) — what posts the COGS legs