# v1.0.1 — operation_date

`issue_date` is now always today, and a new `operation_date` carries the date the service was actually rendered.

Mar 26, 2026 · Breaking

The issue_date of an invoice is now always the day it is actually issued in BeeL., when its billing record is generated, and a new operation_date field lets you record when the operation actually took place.

## What else changed

- New `operation_date` field on invoices — use when invoicing for a past operation (e.g., services delivered last month but invoiced this month)
- `issue_date` is now read-only and always set to today per VeriFactu regulations
- `issue_date` removed from required fields in CreateInvoiceRequest
- Duplicate invoice no longer accepts a custom `issue_date` — duplicates are always dated today
- Idempotency header renamed from `X-Idempotency-Key` to `Idempotency-Key` (standard naming)
- Improved `due_date` documentation — must be same as or after today's date
- New `start_date` field on recurring invoice creation

## Endpoints

- `POST /v1/invoices` — operation_date replaces issue_date in request body
- `PUT /v1/invoices/{invoice_id}` — operation_date (nullable) replaces issue_date
- `POST /v1/invoices/{invoice_id}/duplicate` — issue_date param removed from request

## Where to go next

- [Invoice API Reference](/invoices/listInvoices)
- [VeriFactu Guide](/verifactu)

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Full OpenAPI spec: https://docs.beel.es/api/openapi