> ## Documentation Index
> Fetch the complete documentation index at: https://docs.contazen.ro/llms.txt
> Use this file to discover all available pages before exploring further.
# Check for duplicate expense
> Probe the firm's books for an existing expense that would collide with a prospective payload. Useful before posting a scanned receipt.
## When to use
Call this **before** [`POST /expenses`](./create) when the source is unattended (OCR, recurring import, supplier sync). The response tells the UI whether to surface a confirmation dialog ("an expense from this supplier with this reference already exists — continue?") instead of silently posting a duplicate.
The endpoint never modifies state. Match resolution mirrors the server-side detector used by the OCR + import flows.
## Request
Send either `supplier_id` (preferred — Romanian companies often share name prefixes) or `supplier_data` with the resolved name/CUI from the receipt. The endpoint **never auto-creates** a supplier; if the supplier\_data block doesn't match an existing row, the supplier match is treated as missing and only `reference`-based matches are considered.
CzUid of the matched supplier. Preferred when known.
Fallback when `supplier_id` is unknown. Resolved by CUI first (with `RO` prefix stripped), then by exact name match.
* `name` — supplier name as printed on the document
* `cui` — supplier CUI / VAT number, with or without `RO` prefix
Document number (factura, chitanță, bon fiscal). Used for both exact and `likely` cross-supplier matches.
Issue date in `YYYY-MM-DD`. Combined with supplier + amount for `strong` matches.
Net amount (subtotal). Compared with ±0.02 tolerance to forgive rounding.
Three-letter ISO code. Defaults to `RON`.
## Match types
| `match_type` | Trigger |
| ------------ | ----------------------------------------------------------------- |
| `exact` | Same supplier + same reference |
| `strong` | Same supplier + same date + amount within ±0.02 |
| `likely` | Same reference under a different supplier (review before posting) |
`exact` and `strong` should usually block; `likely` deserves a confirmation but isn't necessarily a true duplicate (e.g. invoice numbers reset per fiscal year across suppliers).
## Response
`duplicate` is `null` when no candidate matches. When populated, the `id` is the CzUid of the existing expense — fetch it via [`GET /expenses/{id}`](./retrieve) for the full record.
```json theme={null}
{
"data": {
"duplicate": {
"id": "Q9hjAB",
"reference": "65776",
"date": "2026-04-25",
"amount": 147.53,
"currency": "RON",
"match_type": "exact"
}
}
}
```
## Errors
* **400** — invalid JSON body or missing required fields when neither `supplier_id` nor `supplier_data.name` is provided
* **401** — missing / invalid bearer token
* **403** — API key lacks `read` permission on expenses
## OpenAPI
````yaml POST /expenses/check-duplicate
openapi: 3.1.0
info:
title: Contazen API
version: 1.2.0
description: >
Build powerful integrations with the Contazen invoicing platform. The
Contazen API is organized around REST,
has predictable resource-oriented URLs, accepts JSON request bodies, returns
JSON-encoded responses,
and uses standard HTTP response codes, authentication, and verbs.
## Authentication
The API uses Bearer token authentication. Include your API key in the
Authorization header.
### Getting your API Key
1. Log in to your Contazen account
2. Navigate to Settings > API
3. Generate or copy your API key (starts with `sk_live_` for production or
`sk_test_` for testing)
### Using the API Key
Include your API key in the Authorization header:
```
Authorization: Bearer sk_live_YOUR_API_KEY
```
### Example Request with cURL
```bash
curl --request GET \
--url https://api.contazen.ro/v1/clients \
--header 'Authorization: Bearer sk_live_YOUR_API_KEY' \
--header 'Accept: application/json'
```
## Rate Limiting
- 1000 requests per hour per API key
- 100 create operations per minute per API key
Rate limit information is included in response headers:
- `X-RateLimit-Limit`: Maximum requests allowed
- `X-RateLimit-Remaining`: Requests remaining
- `X-RateLimit-Reset`: Reset time (Unix timestamp)
## Pagination
All list endpoints return paginated results with the following format:
```json
{
"success": true,
"data": {
"object": "list",
"data": [...],
"has_more": true,
"total": 245,
"page": 1,
"per_page": 50,
"total_pages": 5
},
"meta": {
"version": "v1",
"request_id": "req_1a2b3c4d",
"response_time": "23.45ms"
}
}
```
## Multi-Work-Point Access
API keys belong to a specific work point but can access data from all work
points
within the same parent company.
## Error Handling
The API uses conventional HTTP response codes to indicate success or
failure.
In general: 2xx codes indicate success, 4xx codes indicate an error due to
the
information provided, and 5xx codes indicate an error with Contazen's
servers.
## Expanding Nested Objects
Many endpoints support the `expand` parameter to include related objects in
the response.
This follows the Stripe API pattern. For example:
- `expand[]=lines` - Include invoice line items
- `expand[]=payments` - Include payment records
- `expand[]=client` - Include full client object
## Localization
The API supports multiple languages through:
- `locale` query parameter (en, ro)
- `Accept-Language` header
- Default: English
contact:
name: Contazen Support
email: support@contazen.ro
url: https://contazen.ro
license:
name: Proprietary
url: https://www.contazen.ro/termeni-si-conditii-de-utilizare/
servers:
- url: https://api.contazen.ro/v1
description: Production API server
security:
- bearerAuth: []
tags:
- name: Authentication
description: API authentication and test endpoints
- name: Clients
description: Manage your customers (B2B and B2C)
- name: Invoices
description: Create and manage invoices, proformas, and receipts
- name: Products
description: Manage your product and service catalog
- name: Expenses
description: Track and manage business expenses
- name: Expense Categories
description: Organize expenses with categories
- name: Suppliers
description: Manage expense suppliers and vendors
- name: Settings
description: API settings and configuration
- name: Payments
description: Payments received against invoices
- name: Receipts
description: Cash receipts (chitanțe) — standalone or paired with an invoice
- name: Company Lookup
description: Romanian company lookup (ANAF / VIES)
- name: Invoice Series
description: Manage invoice numbering series
- name: Bank Accounts
description: Manage IBAN bank accounts
- name: E-Factura
description: Romanian e-invoicing status and configuration
- name: Supplier Bills
description: Supplier invoices imported from the ANAF SPV inbox
- name: VAT Rates
description: Firm-scoped custom VAT rates on top of the Romanian catalog
- name: Currencies
description: Currencies enabled for the firm's bill templates
- name: Languages
description: Languages enabled for the firm's bill templates
- name: Conta
description: |
Public ANAF data for the firm's CUI: fiscal profile (TVA scope, RTVAI,
split TVA, status, e-Factura registration, CAEN) and annual balance
sheets (cifra de afaceri, profit, capitaluri, datorii, salariați).
Powered by the public ANAF webservices (no OAuth required for these
endpoints). The data is cached locally and refreshed on demand via
the `/sync` actions.
paths:
/expenses/check-duplicate:
post:
tags:
- Expenses
summary: Pre-check for duplicate expense
description: |
Probe the firm's books for an existing expense that would collide
with the prospective payload (same supplier + reference, or same
supplier + date + amount within tolerance). Useful before posting a
scanned receipt to surface a confirmation dialog.
Returns `{ duplicate: null }` when nothing matches, or a payload
describing the existing row otherwise. Match types:
- `exact` — supplier + reference
- `strong` — supplier + date + amount (±0.02)
- `likely` — reference collision across suppliers
operationId: checkExpenseDuplicate
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
supplier_id:
type: string
description: Supplier CzUid (preferred) or omit and send `supplier_data`.
supplier_data:
type: object
properties:
name:
type: string
cui:
type: string
reference:
type: string
date:
type: string
format: date
amount:
type: number
currency:
type: string
default: RON
responses:
'200':
description: Duplicate check result
content:
application/json:
schema:
type: object
properties:
duplicate:
nullable: true
type: object
properties:
id:
type: string
reference:
type: string
nullable: true
date:
type: string
format: date
amount:
type: number
currency:
type: string
match_type:
type: string
enum:
- exact
- strong
- likely
components:
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: Use your API key (sk_live_xxx or sk_test_xxx)
````