---
search:
  tags:
    - projects
    - POST
seo:
  description: >-
    Creates a new interim payment (partial payment, advance… Reference for the
    POST /projects/{projectId}/interim-payments endpoint in the Leadtime Public
    API API.
sidebar:
  badge: POST
  label: Create interim payment
title: Create interim payment
type: openapi-operation
---
Creates a new interim payment (partial payment, advance payment, prepayment) in the specified project.

**How it works:**
- The new payment is added to the project with the provided title, description, and amount
- Sort order is automatically set to the maximum existing sort order plus 1 (appears at the end of the list)
- The payment is initially marked as not billed (isBilled: false)
- Description can be provided as HTML or Markdown and is automatically converted to internal IDoc format

**Required fields:**
- **title**: Short label for the payment (e.g., "Prepayment", "50% Deposit", "Milestone 1")
- **amount**: Payment amount (must be positive, minimum 0.01)

**Optional fields:**
- **description**: Detailed notes about the payment (e.g., "Client paid €1,000 upfront"). Can be provided as HTML or Markdown format

**What happens after creation:**
- The payment becomes available for billing in the invoicing system
- When used in an invoice, it is automatically deducted from the final invoice amount
- The payment can be reordered using the sort endpoint

**Validation:**
- Amount must be a positive number (minimum 0.01)
- Title cannot be empty
- Project must exist and be accessible

**Permissions:** Requires Projects.edit permission

<Operation source="api-reference" id="projectinterimpaymentscontroller-createinterimpayment" />