> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syrto.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Look up companies by tax ID

> Batch resolve up to 20 tax IDs to company IDs in a single call.

`syrto_lookup_companies_by_tax_id` resolves a list of Italian tax IDs (codice fiscale or partita IVA) into `company_id` values. Each tax ID is checked against both the EU VAT number and the taxpayer identification number on file.

<Tip>
  For looking up a single company by name or tax ID, use [`syrto_find_company`](/mcp/tools/find-company) instead. This tool is designed for batch resolution when you already have multiple tax IDs.
</Tip>

## Use this tool to

* Resolve multiple tax IDs to company IDs in one call (up to 20)
* Check which tax IDs match a known company and which do not
* Get the `company_id` required by most other Syrto tools when starting from tax identifiers

**Related tools:** For single-company lookup by name or tax ID, use [Find company](/mcp/tools/find-company).

## Arguments

<ParamField query="queries" type="string[]" required>
  List of tax IDs to resolve (min 1, max 20). Each entry can be up to 200 characters. Each tax ID is matched against both EU VAT number and taxpayer identification number fields.

  **Example:** `["01654010345", "00159560366"]`
</ParamField>

<ParamField query="language" type="string">
  `"en"` for English (default) or `"it"` for Italian.
</ParamField>

## Returns

A JSON list in the same order as the input `queries`. Each item contains:

<ResponseField name="query" type="string">
  The original tax ID from the request.
</ResponseField>

<ResponseField name="status" type="string">
  `"resolved"` if a matching company was found, `"not_found"` otherwise.
</ResponseField>

<ResponseField name="company" type="object | null">
  Present when `status` is `"resolved"`. Contains:

  * `id` — the `company_id` to pass to all other Syrto tools
  * `legal_name` — official registered company name
  * `eu_vat_number` — EU VAT number (`null` if not available)
  * `taxpayer_identification_number` — Italian codice fiscale (`null` if not available)
</ResponseField>

## Example

**Resolve two tax IDs:**

```json theme={null}
{
  "queries": ["01654010345", "00000000000"]
}
```

**Response:**

```json theme={null}
{
  "result": [
    {
      "query": "01654010345",
      "status": "resolved",
      "company": {
        "id": "Zm86SVRfMDE2NTQwMTAzNDVfVTox",
        "legal_name": "BARILLA G. E R. FRATELLI - SOCIETÀ PER AZIONI",
        "eu_vat_number": "01654010345",
        "taxpayer_identification_number": "01654010345"
      }
    },
    {
      "query": "00000000000",
      "status": "not_found",
      "company": null
    }
  ]
}
```