# POST /api/invoicing/invoices/{invoiceId}/payment-plan/pay-installment

Payment Plan: Records a manual (offline) payment for a single pending installment: applies
its amount to the invoice balance and marks the installment collected. Returns the updated
invoice.

**Required permissions**: `Invoicing.Invoices`, `Invoicing.Invoices.PaymentPlan`  
**Scope**: merchant

**Operation ID:** `POST_api_invoicing_invoices_invoiceId_payment-plan_pay-installment`

## Authorization

Requires: Invoicing.Invoices, Invoicing.Invoices.PaymentPlan, merchant scope.

Required permissions:
- `Invoicing.Invoices`
- `Invoicing.Invoices.PaymentPlan`

## Parameters

| Name | In | Required | Type | Description |
| --- | --- | --- | --- | --- |
| invoiceId | path | yes | string(uuid) |  |
| suppressNulls | query | no | boolean | If true, omit properties with null values. |

## Request Body

**Content type:** `application/json`

Schema: `WinkPGInvoicingPayInstallmentInput`

**Content type:** `text/json`

Schema: `WinkPGInvoicingPayInstallmentInput`

**Content type:** `application/*+json`

Schema: `WinkPGInvoicingPayInstallmentInput`

## Responses

### 200

OK

**Content type:** `text/plain`

Schema: `WinkPGInvoicingInvoiceDto`

**Content type:** `application/json`

Schema: `WinkPGInvoicingInvoiceDto`

**Content type:** `text/json`

Schema: `WinkPGInvoicingInvoiceDto`

### 403

Forbidden

**Content type:** `text/plain`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `text/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

### 401

Unauthorized

**Content type:** `text/plain`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `text/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

### 400

Bad Request

**Content type:** `text/plain`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `text/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

### 404

Not Found

**Content type:** `text/plain`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `text/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

### 501

Not Implemented

**Content type:** `text/plain`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `text/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

### 500

Internal Server Error

**Content type:** `text/plain`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

**Content type:** `text/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

### default

The request failed. The body carries the standard error envelope: a machine-readable `error.code`, a human-readable `error.message`, and `error.validationErrors` when the failure was a validation rejection. See the error-code reference in this document's description for the values `error.code` can take.

**Content type:** `application/json`

Schema: `WinkPGHttpRemoteServiceErrorResponse`

## See also

- [All documentation](https://docs.winkpg.io/llms.txt): the machine-readable index of every public page on this site.