# POST /api/invoicing/invoices/{id}/payment-plan

Payment Plan: Sets up a plan against the outstanding balance.

Applies to an issued invoice, and returns the updated invoice.

**Operation ID:** `invoicePaymentPlanCreate`

## Authorization

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

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

## Parameters

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

## Request Body

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

Schema: `CreatePaymentPlanInput`

Properties:
- `installmentCount` (integer(int32)): Number of equal installments to split the balance into. Ignored when `customAmounts` is supplied. Conditional: When CustomAmounts is null or CustomAmounts.Count == 0. Range: 2 to 60.
- `firstDueDate` (string(date-time)) required: The due date of the first installment. Subsequent due dates are spaced by `frequency`.
- `frequency` (object): The cadence between installment due dates.
- `autoCollect` (boolean): When true, each installment is auto-charged against `paymentTokenId` as it comes due.
- `paymentTokenId` (string(uuid)): The stored payment-method token to auto-charge. Required when `autoCollect` is true. Required: When AutoCollect is true.
- `customAmounts` (array<number(double)>): Optional explicit per-installment amounts. When supplied, they must sum to the invoice balance. Conditional: When CustomAmounts is not null and CustomAmounts.Count > 0.

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

Schema: `CreatePaymentPlanInput`

Properties:
- `installmentCount` (integer(int32)): Number of equal installments to split the balance into. Ignored when `customAmounts` is supplied. Conditional: When CustomAmounts is null or CustomAmounts.Count == 0. Range: 2 to 60.
- `firstDueDate` (string(date-time)) required: The due date of the first installment. Subsequent due dates are spaced by `frequency`.
- `frequency` (object): The cadence between installment due dates.
- `autoCollect` (boolean): When true, each installment is auto-charged against `paymentTokenId` as it comes due.
- `paymentTokenId` (string(uuid)): The stored payment-method token to auto-charge. Required when `autoCollect` is true. Required: When AutoCollect is true.
- `customAmounts` (array<number(double)>): Optional explicit per-installment amounts. When supplied, they must sum to the invoice balance. Conditional: When CustomAmounts is not null and CustomAmounts.Count > 0.

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

Schema: `CreatePaymentPlanInput`

Properties:
- `installmentCount` (integer(int32)): Number of equal installments to split the balance into. Ignored when `customAmounts` is supplied. Conditional: When CustomAmounts is null or CustomAmounts.Count == 0. Range: 2 to 60.
- `firstDueDate` (string(date-time)) required: The due date of the first installment. Subsequent due dates are spaced by `frequency`.
- `frequency` (object): The cadence between installment due dates.
- `autoCollect` (boolean): When true, each installment is auto-charged against `paymentTokenId` as it comes due.
- `paymentTokenId` (string(uuid)): The stored payment-method token to auto-charge. Required when `autoCollect` is true. Required: When AutoCollect is true.
- `customAmounts` (array<number(double)>): Optional explicit per-installment amounts. When supplied, they must sum to the invoice balance. Conditional: When CustomAmounts is not null and CustomAmounts.Count > 0.

## Responses

### 200

OK

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

Schema: `InvoiceDto`

Properties:
- `extraProperties` (object)
- `id` (string(uuid))
- `creationTime` (string(date-time)): The date and time when this entity was created.
- `creatorId` (string(uuid)): The ID of the user who created this entity.
- `lastModificationTime` (string(date-time)): The date and time when this entity was last modified.
- `lastModifierId` (string(uuid)): The ID of the user who last modified this entity.
- `isDeleted` (boolean): Indicates whether this entity has been deleted.
- `deleterId` (string(uuid)): The ID of the user who deleted this entity, if it is deleted.
- `deletionTime` (string(date-time)): The date and time when this entity was deleted, if it is deleted.
- `tenantId` (string(uuid))
- `billerId` (string(uuid))
- `billerType` (InvoicePartyType): Identifies the type of entity acting as the biller or recipient on an invoice.
- `recipientId` (string(uuid))
- `recipientType` (InvoicePartyType): Identifies the type of entity acting as the biller or recipient on an invoice.
- `invoiceNumber` (string)
- `status` (InvoiceStatus): Represents the lifecycle status of an invoice.
- `isLocked` (boolean)
- `billerSnapshot` (InvoicePartySnapshotDto): Read DTO for denormalized biller/recipient info frozen at invoice issuance.
- `recipientSnapshot` (InvoicePartySnapshotDto): Read DTO for denormalized biller/recipient info frozen at invoice issuance.
- `currency` (string)
- `subtotal` (number(double))
- `taxTotal` (number(double))
- `discountTotal` (number(double))
- `grandTotal` (number(double))
- `amountPaid` (number(double))
- `balanceDue` (number(double))
- `invoiceLevelDiscount` (InvoiceDiscountDto): DTO for an invoice-level discount.
- `issueDate` (string(date-time))
- `dueDate` (string(date-time))
- `sentAt` (string(date-time))
- `viewedAt` (string(date-time))
- `paidAt` (string(date-time))
- `paymentTermsValue` (object)
- `customPaymentDays` (integer(int32))
- `allowPartialPayment` (boolean)
- `minimumPaymentAmount` (number(double))
- `partialPaymentTolerance` (number(double))
- `allowedPaymentMethods` (array<string>)
- `vaultRestriction` (object)
- `applyConvenienceFee` (boolean): Per-invoice override of the merchant's convenience fee on this invoice's payments.  `null` inherits the merchant and feature decision. `true` applies the fee only  when invoice convenience fees are enabled for the tenant.
- `depositRequest` (object): The deposit request on this invoice, if any. Null when no deposit was requested.
- `hppPageId` (string(uuid))
- `templateId` (string(uuid))
- `sourceType` (object)
- `sourceReferenceId` (string)
- `notes` (array<EntityNote>)
- `recipientNote` (string)
- `footerText` (string)
- `reminderConfig` (InvoiceReminderConfigDto): DTO for invoice reminder configuration. Each member overrides the tenant's reminder default on its  own; a member that is null or omitted inherits that default.
- `lineItems` (array<InvoiceLineItemDto>)
- `payments` (array<InvoicePaymentDto>)
- `activities` (array<InvoiceActivityDto>)
- `customFields` (array<CustomFieldValueDto>)
- `concurrencyStamp` (string)
- `entityVersion` (integer(int32))

### 403

Forbidden

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 401

Unauthorized

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 400

Bad Request

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 404

Not Found

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 501

Not Implemented

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 500

Internal Server Error

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 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: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

### 429

The request was refused because a rate limit was exceeded, or because something a later retry can clear stopped it. A rate limit refusal carries an `application/problem+json` body: wait at least the interval `Retry-After` names before retrying, then back off. Limits are tuned per deployment, so read the allowance from the response headers rather than assuming a fixed ceiling. Any other refusal carries the standard error envelope as `application/json`, and its `error.code` names the cause.

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

Schema: `RateLimitProblemDetails`

Properties:
- `type` (string) required: The problem type identifier. Always the same value: the failure is the status code itself,  so there is no sub-type for a caller to branch on.
- `title` (string) required: A short, human-readable summary of the problem type.
- `status` (integer(int32)) required: The HTTP status code, repeated in the body as the problem-details format defines.
- `detail` (string) required: A human-readable explanation of this occurrence of the problem.
- `retryAfterSeconds` (integer(int32)) required: How long to wait before retrying, in whole seconds, carrying the same figure as the  `Retry-After` header. Always at least one: a value of zero would invite an immediate  retry that is certain to be rejected again.

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

Schema: `RemoteServiceErrorResponse`

Properties:
- `error` (RemoteServiceErrorInfo)

## Example request

Every block below sends the same request. Replace {{BASE_URL}} with the address of the API you are calling and {{API_KEY}} with your own key.

The request body is a CreatePaymentPlanInput. See the Request body section below for its fields.

### cURL

```bash
curl -X POST "{{BASE_URL}}/api/invoicing/invoices/{id}/payment-plan" \
  -H "api-key: {{API_KEY}}" \
  -H "Content-Type: application/json" \
  -d '{
  "firstDueDate": "2026-01-01T00:00:00Z"
}'
```

### PowerShell

```powershell
$headers = @{
    'api-key' = '{{API_KEY}}'
}

$body = @'
{
  "firstDueDate": "2026-01-01T00:00:00Z"
}
'@

$response = Invoke-RestMethod -Method POST -Uri '{{BASE_URL}}/api/invoicing/invoices/{id}/payment-plan' `
    -Headers $headers -ContentType 'application/json' -Body $body
```

### TypeScript (SDK)

```bash
npm install @winkpg/winkpg-api
```

```typescript
import { Configuration, InvoicingApi } from '@winkpg/winkpg-api';

const api = new InvoicingApi(new Configuration({
  basePath: '{{BASE_URL}}',
  apiKey: '{{API_KEY}}',
}));

const { data } = await api.invoicePaymentPlanCreate("3fa85f64-5717-4562-b3fc-2c963f66afa6", {
  "firstDueDate": "2026-01-01T00:00:00Z"
});
```

### TypeScript (raw HTTP)

```typescript
const response = await fetch('{{BASE_URL}}/api/invoicing/invoices/{id}/payment-plan', {
  method: 'POST',
  headers: {
    "api-key": "{{API_KEY}}",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "firstDueDate": "2026-01-01T00:00:00Z"
  }),
});

const data = await response.json();
```

### C# (SDK)

```bash
dotnet add package WinkPg.Api.Client
```

```csharp
using WinkPg.Api.Client.Api;
using WinkPg.Api.Client.Client;
using System.Text.Json;

var config = new Configuration { BasePath = "{{BASE_URL}}" };
config.AddApiKey("api-key", "{{API_KEY}}");

var api = new InvoicingApi(config);
var body = JsonSerializer.Deserialize<CreatePaymentPlanInput>("""
    {
      "firstDueDate": "2026-01-01T00:00:00Z"
    }
    """);

var result = await api.InvoicePaymentPlanCreateAsync(Guid.Parse("3fa85f64-5717-4562-b3fc-2c963f66afa6"), body);
```

### C# (raw HTTP)

```csharp
using System.Text;

using var http = new HttpClient { BaseAddress = new Uri("{{BASE_URL}}") };

var request = new HttpRequestMessage(new HttpMethod("POST"), "/api/invoicing/invoices/{id}/payment-plan");
request.Headers.Add("api-key", "{{API_KEY}}");

request.Content = new StringContent("""
    {
      "firstDueDate": "2026-01-01T00:00:00Z"
    }
    """, Encoding.UTF8, "application/json");

var response = await http.SendAsync(request);
response.EnsureSuccessStatusCode();
var json = await response.Content.ReadAsStringAsync();
```

### Python (SDK)

```bash
pip install winkpg-api
```

```python
import winkpg_api

configuration = winkpg_api.Configuration(host="{{BASE_URL}}")
configuration.api_key["ApiKey"] = "{{API_KEY}}"

with winkpg_api.ApiClient(configuration) as client:
    api = winkpg_api.InvoicingApi(client)
    body = winkpg_api.CreatePaymentPlanInput.from_dict({
      "firstDueDate": "2026-01-01T00:00:00Z"
    })
    result = api.invoice_payment_plan_create("3fa85f64-5717-4562-b3fc-2c963f66afa6", body)
```

### Python (raw HTTP)

```bash
pip install requests
```

```python
import requests

headers = {
    "api-key": "{{API_KEY}}",
    "Content-Type": "application/json",
}

body = {
  "firstDueDate": "2026-01-01T00:00:00Z"
}

response = requests.request(
    "POST",
    "{{BASE_URL}}/api/invoicing/invoices/{id}/payment-plan",
    headers=headers,
    json=body,
)
response.raise_for_status()
data = response.json()
```

## See also

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