When enabled, we will perform certain actions on requests processed on your site reference using rules configured on your account.



Rule types

Trust Payments Rules

Rules with a Rule ID of “STR-x” (where x is a number) are Trust Payments Rules. e.g. STR-1

We provide a number of pre-defined rules that can be activated on any of your site references (inactive by default). These rules are displayed within the rule manager interface in MyST and can be activated or deactivated by following the instructions outlined on this page. Trust Payments Rules are always performed before User-Defined Rules.


User-Defined Rules

Rules with a Rule ID of “UDR-x” (where x is a number) are User-Defined Rules. e.g. UDR-129

Using MyST, you can create, modify and activate your own custom rules on any of your site references.



Activating rules

Using MyST

Rules can be activated/deactivated on any of your site references by using the MyST Rule Manager.

Click here for further information.


In the POST to Payment Pages

Rules can be activated for individual requests by submitting the unique rule identifier in the ruleidentifier field. Rules specified in the request will lead certain actions to be performed if pre-defined criteria are met (regardless of whether or not said rules are active on your site references). The following code snippet is from an HTML form where two rules – STR-1 and STR-2 – are specified:

<form method="POST" action="<DOMAIN>/process/payments/choice">
<input type="hidden" name="ruleidentifier" value="STR-1">
<input type="hidden" name="ruleidentifier" value="STR-2">
<input type="submit" value="Pay">

Replace <DOMAIN> with a supported domain. Click here for a full list.


Important: Any rule identifiers submitted (e.g. “STR-1”) must be included in the string used to generate your request site security hash. Failure to do so will result in the customer being shown an “Invalid details” error message.



Merchant decline rule

This rule is only supported by acquirers and payment methods that support security code checks.


When active, the STR-1 rule will automatically cancel transactions (update the settle status to 3) when the security code entered by the customer does not match the value held on the bank’s records.

A “Merchant Declined” message will be displayed to your customers on the Payment Pages when they enter an incorrect security code.

If activated in the MyST Rule Manager, the rule will also be enabled for payments processed using the Virtual Terminal, where a message of “Transaction Failed” will be displayed.


If you intend to implement the merchant decline rule on a site reference where redirect and/or notification rules are already active, you should review the additional information provided below and update your rules as required.


Contact our Support Team if you require further assistance.


For merchants with existing rules

When a transaction is cancelled by an update transaction response rule (e.g. Merchant Decline), the error code may remain in status “0” (Ok). This would indicate that the payment was authorised by the acquiring bank, but later cancelled by Trust Payments. Therefore, you may need to update any active rules to take this possible outcome into account. To prevent a rule from being triggered on a merchant decline, remove the settle status “3” (Cancelled) from existing conditions on the affected site reference(s).

Note: When creating new conditions using the MyST Rule Manager, we will automatically deselect settle status “3” when you select errorcode of “0”, by default.