API changelog: 2026

Pausing a filing now follows the same window as the Kintsugi app. After the 15th of the month a filing is due, it can no longer be paused with any pauseIntent, including assistance and skip, which were accepted before. A review pause also needs a pausedUntilDate from today through the 15th of the due month; a date in the past, accepted before, is now refused. A date that is still today anywhere in the world counts as today. POST /filings/{filing_id}/pause answers a refused pause with 400 and code invalid_request, and POST /filings/bulk/pause still answers 200, listing each refused filing in failed.

When a portfolio credential creates an organization with POST /organizations, the name must now be unique, ignoring letter case. A name already in use answers 409 with code conflict and the message An organization with this name already exists. Before, the 2026-07-21 release accepted any name, including one already in use or one that differed only in letter case, such as acme beside Acme. Creating an organization from a user session without a portfolio is unchanged.

When POST /connections/apideck/{conn_id}/activate finds that the shopId belongs to a connection your organization already has, it reactivates that existing connection, removes the one being activated, and answers 400 as before. The error code is now already_connected instead of invalid_request, with the message This store is already connected. The existing connection was reactivated. The store is connected and nothing more is needed. already_connected is a new value of the code field in error responses.

The five endpoints that change addresses now accept the same callers: any member of the organization, a portfolio Owner or Admin who manages it, or an API key for the organization. A portfolio Member now receives 403 with code forbidden from POST /addresses/approve, which accepted them before. The other four, which accepted only the organization's Owner among its own users, now also accept its Admins and Members, who received 403 before. An organization you cannot access still answers 404, and API keys work on all five as before.

On POST /imports/initiate and POST /imports/upload-urls, whether you send userId now depends on your credential. With an API key it is required and must not be blank: a missing userId answers 400 with code invalid_request instead of 422, and an empty or whitespace-only value, accepted before, is now refused the same way. With a signed-in user session, userId is optional and ignored, and the import is recorded under that user.

Deregistering now records when and why the registration closes. POST /v1/registrations/{registration_id}/deregister requires a JSON body with closure_date, reason and final_return_acknowledged, so a request with no body, which succeeded before, is now rejected with 422. The 2026-07-21 release changed the same way, with the fields closureDate, reason and finalReturnAcknowledged.

Creating a credit note with an external_id already used for a credit note on the same original transaction used to fail with 409 Conflict. It now succeeds and returns the stored credit note unchanged. On v1 that response is 200, and creating a new credit note now answers 201 instead of 200. On the 2026-07-21 release the stored credit note comes back with 202, the same as a new one. The same external_id against a different original transaction still returns 409.

Creating a physical nexus for an organization, country, state and category that already has one used to fail with 409 Conflict. It now succeeds and returns the stored record unchanged: the dates and address in the request are not applied. On v1 and the Partner API the response is 200, the same as for a new record. On the 2026-07-21 release it is 200 for an existing record and 201 for a new one.

Creating a product with an external_id and source that already exist used to fail with 409 Conflict. It now succeeds with 200 and returns the stored product unchanged: the fields in the request are not applied. A product you deleted is restored instead, with status PENDING, and is not used in tax calculation until it is approved again. Creating a new product now answers 201 instead of 200.