# Pay in 3 integration

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⏱ 3 min
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👤 Legal Team
###### Wording and placement guidelines for the Ratepay Pay in 3 instalment calculation details

The integration of the [Ratepay instalment calculator](/docs/developer/api_integration/payment_1.8/payment_api_documentation/how_to_integrate_ratepay/pay_in_3/) in case of using the Ratepay payment method Pay in 3 is mandatory.

Whenever Pay in 3 is used, the following details, sent with Ratepay's instalment calculator response, needs to be shown to the customer during checkout:

| Information | Description |
|  --- | --- |
| `<number-of-rates>` months at `<rate>` | Duration and monthly amount |
| `<total-amount>` | Total amount incl. fees and charges |


Additionally you have to show a link or a button, called **Show calculation details / Ratenberechnung anzeigen** to provide the respective calculation details. They have to contain the following details:

| Value | Description |
|  --- | --- |
| `<amount>`Warenwert | Shopping basket amount incl. shipping (Summe aller Artikel Ihres Warenkorbs, inkl. Versandkosten etc.) |
| `<service-charge>`Vertragsabschlussgebühr | Service charge |
| (Bei Ratenzahlung pro Bestellung anfallende, einmalige Bearbeitungsgebühr.) |  |
| `<annual-percentage-rate>`Effektiver Jahreszins | Annual percentage rate of charge |
| (Gesamtkosten des Kredits als jährlicher Prozentsatz.) |  |
| `<interest-rate>`Sollzinssatz p.a. (gebunden) | Debit interest rate |
| (Periodischer Prozentsatz, der auf das in Anspruch genommene Darlehen angewendet wird.) |  |
| `<interest-amount>`Zinsbetrag | Interest rate(Konkreter Geldbetrag, der sich aus den Zinsen ergibt.) |
| `<rate>`Monatliche Rate je | Monthly instalment due(Monatlich fälliger Teilbetrag.) |
| `<last-rate>`Schlussrate | Final/last instalment due(Im letzten Monat fälliger Teilbetrag.) |
| `<total-amount>`Gesamtbetrag | Total amount incl. fees & charges(Summe der vom Käufer zu zahlenden Beträge aus Warenwert, Vertragsabschlussgebühr und Zinsen.) |


An alternative integration requires the prior approval of Ratepay.

For more information on the integration of the Ratepay instalment calculator, see the following pages:

[Instalment Calculations](/docs/developer/api_integration/payment_1.8/payment_api_documentation/the_ratepay_gateway_operations/instalment_calculator/calculation_request/)