---
title: "Apply a late payment fee"
method: POST
path: "/v1/invoices/{invoiceId}/late-fee"
tags: ["Invoices"]
---

# Apply a late payment fee

`POST /v1/invoices/{invoiceId}/late-fee`

## Request

- Base URL: `https://api.frihet.io`
- URL: `https://api.frihet.io/v1/invoices/{invoiceId}/late-fee`
- Auth: API key in header `X-API-Key`

Calculate and apply a late payment fee to an overdue or sent invoice.
Uses the EU Late Payment Directive default rate of 8% per annum if `amount`
is not specified. Can only be applied once per invoice.

## Path parameters

- `invoiceId` string, required

## Request body

- object
  - `amount` number: Fixed fee amount. If omitted, auto-calculated at 8% p.a. on the invoice total.
  - `daysOverdue` integer: Override the number of overdue days used for auto-calculation. Defaults to actual days past due date.

## Response `200`

Late fee applied

- object
  - `success` boolean
  - `feeAmount` number: Fee amount applied
  - `invoiceId` string
  - `daysOverdue` integer

## Other responses

- `400`: Bad request - invalid parameters or request body
- `401`: Authentication required or invalid API key
- `404`: Resource not found
- `429`: Rate limit exceeded (100 requests per minute)
- `500`: Internal server error

---

[API](https://skmtc.dev/frihet/apis/frihet-api.md) · [All operations](https://skmtc.dev/frihet/apis/frihet-api/llms.txt) · [OpenAPI document](https://skmtc.dev/frihet/apis/frihet-api/revisions/3dd37f6a72d1?raw)