What is the Subscription Engine?

You can schedule payments to be processed at regular intervals on your behalf by utilising our Subscription Engine. The Subscription Engine is activated once per day, automatically processing any payments previously scheduled on your account.


  • Your merchant ID must be capable of processing recurring (continuous authority) payments. If in doubt, we strongly recommend contacting your acquiring bank for clarification.
  • Only American Express, Mastercard and Visa branded cards can be used for processing subscription payments. (Maestro is not supported)

Process overview

  • You will need to configure the request submitted to Trust Payments to define the frequency and value of subscription payments.
  • Payments are automatically processed at the specified intervals by our Subscription Engine.


Subscription processes

When processing a subscription, there are two different workflows you can implement:

  • Schedule subscription with immediate payment
    Used to process a payment immediately and schedule a subscription to perform further payments at regular intervals
  • Schedule subscription without immediate payment
    Used to skip the first payment (e.g. a free trial) and schedule a subscription to perform payments at regular intervals

  We recommend merchants processing high-volume recurring transactions enable scheme updates

With the introduction of the new Visa Account Updater (VAU) and Mastercard's Automatic Billing Updater (ABU) systems, Trust Payments can now check with card schemes for updates to the customer's card details prior to subscription payments (e.g. to check whether the customer has been issued a new card) and then automatically use these new card details in subsequent subscription payments for the customer going forward. Once enabled, no additional configuration to your system is needed.

This functionality must be enabled on your site reference(s) before it can be used. Please contact your account manager to register for this solution.



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


Subscription fields


This field indicates the type of subscription to be processed. Your system can submit the following 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). For most merchants, the subscriptiontype should be set to “RECURRING”.
  • “INSTALLMENT” is only used in select cases with certain acquirers*. It is designed for when a customer is purchasing a single order, with payment being collected over several installments (for example, paying £100 a month for an order until it has been paid in full).

  *Installments are supported for merchants with a Trust Payments acquiring account. If you are using a different acquiring bank, you will need to contact our Support Team to check this feature is supported before proceeding.


Unless specified otherwise, subscriptions start with subscriptionnumber = 1 by default. The subscriptionnumber is automatically incremented in every subsequent subscription payment until it exceeds the value of the subscriptionfinalnumber field, when no further payments will be attempted. A completed subscription is represented by a subscriptionnumber that is higher than the corresponding subscriptionfinalnumber.

  We allow you to start a subscription from a higher value than 1. This is to allow you to continue the processing of a previous subscription, while retaining the number of payments that have already been processed.

New subscriptions should always start with subscriptionnumber = 1. Only start with a higher value when resuming a previous subscription, with the same payment details.


Subscription Engine fields


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

  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 used to set the number of payments to be processed over the course of the subscription:

  • If processing a combined AUTH SUBSCRIPTION request:
    If subscriptionnumber = 1
    and subscriptionfinalnumber = 12
    There will be 12 payments in total (The initial AUTH + 11 subscription payments)
  • If processing a combined ACCOUNTCHECK SUBSCRIPTION request:
    If subscriptionnumber = 1
    and subscriptionfinalnumber = 12
    There will be 11 payments in total (The initial ACCOUNTCHECK + 11 subscription payments)
    (The initial ACCOUNTCHECK counts against the final number)

If the subscriptionfinalnumber value is “0”, the Subscription Engine will schedule payments indefinitely until the user manually sets the subscription to Inactive.


This field refers to when the first automated payment will be processed. From there onward, we will use the data submitted in the subscriptionunit and subscriptionfrequency fields (as described above) to automatically process the subscription payments at regular intervals.

e.g. If a subscription request is submitted on 5th January 2018
the interval is 1 MONTH (subscriptionfrequency = 1 and subscriptionunit = MONTH)
and subscriptionbegindate is 2018-01-08,
the first automated payment will be processed on 8th January 2018, and all subsequent payments will be processed on the 8th of each month.

If you do not submit the subscriptionbegindate, we will use the subscriptionunit and subscriptionfrequency fields above to automatically schedule the first automated payment.
e.g. In the same scenario as above, but without submitting the subscriptionbegindate, the first automated payment would be processed on 5th February 2018 (1 MONTH after the original request). All subsequent payments will be processed on the 5th of each month.


Managing subscriptions

Although the Subscription Engine processes payments automatically, you still need to monitor this activity and take action if an issue arises (e.g. if a transaction declines):


Where next?

  Schedule subscription with immediate payment

Your app will need to process a combined THREEDQUERY, AUTH, SUBSCRIPTION request.

Links to documentation:
Payment Pages . JavaScript Library . Android SDK . iOS SDK

  Schedule subscription without immediate payment

Your app will need to process a combined THREEDQUERY, ACCOUNTCHECK, SUBSCRIPTION request.

Links to documentation:
Payment Pages . JavaScript Library . Android SDK . iOS SDK

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