> For the complete documentation index, see [llms.txt](https://dev.ropo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dev.ropo.com/guides/basics/invoice/attachments.md).

# Attachments

Use attachments when the invoice needs extra documents. Typical cases are timesheets, specifications, or signed agreements.

### Supported formats

* PDF
* excel and csv for b2b and peppol invoices

### How to send attachments

You can send multiple attachments. Add them under `dataset.attachment`.

#### Option A: Send file content (`attachmentfile`)

Use this when the attachment is unique per invoice.

```json
{
  "datastream": {
    "dataset": [
      {
        "jobtype": "0",
        "customertype": "1",
        "company": "Example Company",
        "address": "Example street 1",
        "postcode": "00100",
        "city": "Helsinki",
        "billdate": "2026-02-06",
        "paydate": "2026-02-20",
        "payrow": [
          { "desc": "Service", "count": "1", "amount": "100.00", "taxpr": "24" }
        ],
        "attachment": [
          {
            "attachmentname": "specification.pdf",
            "attachmentfile": "<base64-encoded-file>"
          }
        ]
      }
    ]
  }
}
```

#### Option B: Reference a pre-uploaded file (`attachmentid`)

Use this when the same attachment is reused across many invoices.

```json
{
  "datastream": {
    "dataset": [
      {
        "jobtype": "0",
        "customertype": "1",
        "company": "Example Company",
        "address": "Example street 1",
        "postcode": "00100",
        "city": "Helsinki",
        "billdate": "2026-02-06",
        "paydate": "2026-02-20",
        "payrow": [
          { "desc": "Service", "count": "1", "amount": "100.00", "taxpr": "24" }
        ],
        "attachment": [
          { "attachmentid": "2519701" }
        ]
      }
    ]
  }
}
```

### Practical constraints

* Keep margins at least 2 cm in PDF files.
* Keep attachments short. Overlong letters can delay delivery.
* Size of pdf-file containing invoice and attachments is not should not go over one megabyte (1 MB) if invoice is delivered as an e-invoice (b2c, b2b, PEPPOL, Omaposti, Kivra, email)
* Attachment files cannot contain any references to outer resources like links to web-pages or to other documents. Attachment editing or saving it to other formats cannot be blocked.
* If you need many files, consider ZIP uploads.


---

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