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# Processing Recurring PayPal Express Checkout Transactions

To enable PayPal for recurring billing, you must first request and receive permission from PayPal to conduct reference transactions. When permission is granted, you can receive the PayPal `referenceID` required to process recurring billing transactions through PayPal, without requiring the subscriber to log into PayPal for every billing event. See "Enabling the Vindicia Subscribe API to Access PayPal" above.

**Note:**

The section above titled "Implementing the PayPal Transaction Flow" outlines the SOAP API calls for processing a transaction. The instructions below provide additional information about processing one-time transactions.

Recurring PayPal transactions allow your subscribers to set up subscription billing plans, which are processed through PayPal with a one-time subscriber authorization step.

After you receive a PayPal `referenceId` for an initial Subscription transaction, Vindicia Subscribe sends PayPal a Transaction with the Billing Agreement ID (`referenceId`) to initiate all subsequent Subscription payments.

To process recurring PayPal Transactions:

1. For the first SOAP API call, call `AutoBill.update`.

   * Pass in all the information collected from the subscriber.
   * Set the `validatePaymentMethod` flag to `true` to generate the validation transaction necessary to return the required `payPalTransactionId` parameter required for recurring billing.
     Vindicia Subscribe creates a new Subscription object with status `New`. If an Account object for the subscriber does not yet exist, Vindicia Subscribe also creates a new Account for the subscriber.

2. For the second Vindicia Subscribe API call, call `AutoBill.finalizePayPalAuth`.

   * Include the PayPal `referenceId` as an input parameter in the call to enable recurring billing for the Subscription.
     Vindicia Subscribe updates the Subscription.

**Parent topic:**[Using PayPal Express Checkout With Vindicia Subscribe](../topics/r_usingPayPal)


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