# Calculation Request
###### The Calculation Request calculates and returns an installment plan depending on the request parameters and the stored parameters of the merchant profile.
## Request Parameters
### `
` Section
| Parameter | Condition | Enumeration |
| --- | --- | --- |
| `system-id` | Mandatory | |
| `operation` | Mandatory | `CALCULATION_REQUEST` |
| `operation@subtype` | Mandatory | `calculation-by-time` |
| `credential` | Mandatory | |
### `` Section
The `` section of the **CALCULATION_REQUEST request** contains the input parameters for the instalment plan favored by the customer.
| Parameter | Condition | Type |
| --- | --- | --- |
| `installment-calculation` | Mandatory | installmentCalculationType |
### XML Examples
```xml calculation-request-by-time
MyTestsystem
CALCULATION_REQUEST
INTEGRATION_TE_DACH
4c0a11923fa3433fb168f9c7176429e9
200.00
3
```
## Response Parameters
### `` Section
| Parameter | Condition | Enumeration |
| --- | --- | --- |
| `system-id` | Mandatory | |
| `operation` | Mandatory | |
| `operation@subtype` | Mandatory | `calculation-by-time` |
| `response-type` | Mandatory | - `INSTALLMENT_PLAN`- `STATUS_ERROR` |
| `processing` | Mandatory | |
### `` Section
The `` section of the **CALCULATION_REQUEST response** contains the details of the calculated instalment plan.
| Parameter | Condition | Type |
| --- | --- | --- |
| `installment-calculation-result` | Mandatory | installmentCalculationResultType |
### XML Examples
```xml by-time
MyTestsystem
CALCULATION_REQUEST
INSTALLMENT_PLAN
2016-03-29T13:37:08.000
Successfully
Calculation reason: FULFILLED_CONDITION: The payment plan fulfilled the conditions.
Calculation successful
200
200
0
0
0
0
0
3
66.67
66.66
2
```
## How the instalment calculation result of the CALCULATION_REQUEST maps to the instalment details of the PAYMENT_REQUEST
Some parameters of the **Calculation Request response** must be passed to the Gateway with the subsequent **Payment Request request**. The following illustration demonstrates how those parameters are mapped.
Mapping of Calculation Request results to Payment Request parameters
### Mapping Table
| **CALCULATION_REQUEST**Response parameters | = | **PAYMENT_REQUEST**Request parameters |
| --- | --- | --- |
| `total-amount` | = | `amount` |
| `àmount` | = | `shopping-basket@amount` |
| `interest-rate` | = | `interest-rate` |
| `number-of-rates` | = | `installment-number` |
| `rate` | = | `installment-amount` |
| `last-rate` | = | `last-installment-amount` |
| `payment-firstday` | = | `payment-firstday` |