Upload or replace a filing artifact
Store a filing's return or payment confirmation document, as multipart/form-data with the PDF in the file part. artifactType picks the slot: RETURN or PAYMENT. Uploading to a slot that already holds a document replaces it. Only a caller that files the organization's returns itself may upload: a partner with self-managed filings enabled (its portfolio key, or a partner user who can see the organization), or the organization's own ADMIN, OWNER or organization key when such a partner manages it. Send an Organization-Id, Connection-Id or Entity-Id selector to say which organization the filing belongs to. The filing's status does not change. Download the stored document through GET /attachments/{id}/download.
The file must be a PDF of at most 10 MB. Returns 404 if the filing does not exist or belongs to an organization your credential cannot access, 403 if Kintsugi files the organization's returns or your credential is not its filer, 409 if the filing is not in the FILING or FILED status, 413 if the file is too large, and 422 if it is not a PDF.
Authorization
Headers
Release date, as YYYY-MM-DD. Defaults to 2026-07-21.
Target organization id (Organization-Id selector).
Target connection id; resolves to its organization.
Platform entity id; resolves to a connection's organization.
Optional source to disambiguate an Entity-Id.
Path parameters
The unique identifier of the filing.
Which confirmation document the upload fills.
RETURNPAYMENTResponse
Kintsugi's unique identifier for the attachment.
Name the file was uploaded under.
Media type of the file.
Size of the file in bytes.
When the attachment was uploaded, as an RFC-3339 UTC timestamp.
Successful Response
The request was invalid.
Authentication failed or was missing.
The credential is not permitted for this request.
The requested resource was not found.
The request conflicts with existing state.
The request body is larger than this endpoint accepts.
The request failed validation.
A service this request depends on was unavailable. Retry the request.