---
updatedAt: 2026-08-19T14:46:25.000Z
agentTools:
  projectIndex: https://ae.docs.digitax.tech/llms.txt
---

# Credit notes calculations and validations

Shares all invoice validations (issue-date window, items, allowances/charges, delivery, transaction types) — differences only:

* `credit_note_reason_code`: valid code if provided.
* `original_invoice_id`: required unless reason is *Volume Discount*.
* **Type mapping to original invoice**: `380→381`, `480→81`, `389→261`. Type `81` carries the same E/O/Z + `company_id` restriction as `480`. Type `261` (self-billed credit note) needs the branch company/postal check — same bypass gap as self-billed invoices above.

**When **`original_invoice_id`** is provided:**

* Must reference an invoice, not another credit note.
* `customer_party_id` (or `supplier_id` for self-billed) must match the original.
* `issue_date` ≥ original's `issue_date`.
* `document_currency_code` and `tax_currency_exchange_rate` (if provided) must match the original.
* `transaction_types`, if provided, must match the original; otherwise inherited.
* Every credit-note item must reference an item on the original invoice.
* Per-item line amount can't exceed the original line; cumulative credited amount across all prior credit notes for that item can't exceed the original line amount.
* Total `payable_amount` can't exceed the original invoice's.