Subscription engine


You can schedule payments to be processed at regular intervals on your behalf by utilising our subscription engine. This is achieved by processing standard Authorisations using the Payment Pages, along with additional fields to schedule subscriptions. The additional fields define how many Subscription payments are to be processed and the interval between the payments. Our subscription engine is activated once per day, automatically processing any payments previously-scheduled on your account.

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Subscription payments require no further input from your system to be processed successfully at regular intervals, providing the initial request is processed successfully and has followed our specification.



Process overview

What will the customer see?

  • During the checkout process, the customer will be prompted for their address and card details.
  • The checkout asks the customer to agree to a subscription, and clearly states when payments will be processed and how much the customer will pay.
  • Payments are automatically processed at the specified intervals by our subscription engine.


How does it work behind the scenes?

  1. The customer is redirected to Payment Pages and follows the instructions displayed on screen.
  2. We do the rest: Payments are automatically processed at the intervals specified in the initial request.






Subscription fields

To schedule the subscription in our subscription engine, you will need to understand the definition of each subscription field.



This field represents the unit of time between each subscription. This can be either “DAY” or “MONTH”.

Note: It is imperative that this field is submitted to the gateway in CAPITALS (“DAY” or “MONTH”).



Combined with unit, the frequency defines how frequently payments are processed.

e.g. For one payment every 7 days: subscriptionfrequency = 7 and subscriptionunit = DAY

e.g. For one payment every 2 months: subscriptionfrequency = 2 and subscriptionunit = MONTH



This is the total number of payments to be processed over the course of the subscription.

Note: If the value is “0”, the subscription engine will schedule payments indefinitely until the user manually sets the subscription to Inactive.



This field indicates the type of subscription to be processed. Your system can submit these two values:

  • RECURRING is used when the customer is performing a recurring payment for a new product/service each time (for example, a magazine subscription).
  • INSTALLMENT is only used in select cases with certain acquirers. It is designed for when a customer is purchasing a single item, with payment being collected over several installments (for example, paying £100 a month for an item until it has been paid in full).

Note: Installments are only accepted by certain acquirers. For further info, please contact your bank.



This field refers to when the first automated payment will be processed. Following this, we will automatically process the subscription payments at regular intervals (defined in subscriptionunit and subscriptionfrequency fields).


e.g. If request is processed on 5th Jan 2018, with interval of 1 MONTH and begin date of 2018-01-08,

the first automated payment will be processed on 8th Jan 2018, with later payments processed on 8th of each month.


If you do not submit the begin date, we will use the unit and frequency fields to schedule the first automated payment.
e.g. With the same example as above without the begin date, the first automated payment would be processed on 5th Feb 2018 (1 MONTH after the request). Subsequent payments will be processed on the 5th of each month.



Scheme updates


We strongly recommend that merchants processing high volume recurring transactions enable scheme updates.


We only support this functionality with supported acquiring banks.


This functionality must be enabled on your site reference(s) before it can be used.

Please contact our Support team to discuss enabling scheme updates.


Scheme updates involve Trust Payments contacting the Visa Account Updater (VAU) and Mastercard’s Automatic Billing Updater (ABU) systems to check for updates, and to store any updated payment credentials on our secure servers. These updated payment credentials will automatically be used in future payments in this sequence.

If SCHEMEUPDATE is enabled on the site reference, this will be automatically processed in the days preceding an automated Subscription payment.


It is possible for subscriptions to be “Stopped” following a Scheme update. This can occur if the customer contacts their acquiring bank to cancel the subscription. If this occurs, the SUBSCRIPTION active status is updated to “3” (“Stopped”), and no further payments will be processed.